f8f931bba0
Recent changes are putting more pressure on THP deferred split queues: under load revealing long-standing races, causing list_del corruptions, "Bad page state"s and worse (I keep BUGs in both of those, so usually don't get to see how badly they end up without). The relevant recent changes being 6.8's mTHP, 6.10's mTHP swapout, and 6.12's mTHP swapin, improved swap allocation, and underused THP splitting. Before fixing locking: rename misleading folio_undo_large_rmappable(), which does not undo large_rmappable, to folio_unqueue_deferred_split(), which is what it does. But that and its out-of-line __callee are mm internals of very limited usability: add comment and WARN_ON_ONCEs to check usage; and return a bool to say if a deferred split was unqueued, which can then be used in WARN_ON_ONCEs around safety checks (sparing callers the arcane conditionals in __folio_unqueue_deferred_split()). Just omit the folio_unqueue_deferred_split() from free_unref_folios(), all of whose callers now call it beforehand (and if any forget then bad_page() will tell) - except for its caller put_pages_list(), which itself no longer has any callers (and will be deleted separately). Swapout: mem_cgroup_swapout() has been resetting folio->memcg_data 0 without checking and unqueueing a THP folio from deferred split list; which is unfortunate, since the split_queue_lock depends on the memcg (when memcg is enabled); so swapout has been unqueueing such THPs later, when freeing the folio, using the pgdat's lock instead: potentially corrupting the memcg's list. __remove_mapping() has frozen refcount to 0 here, so no problem with calling folio_unqueue_deferred_split() before resetting memcg_data. That goes back to 5.4 commit87eaceb3fa
("mm: thp: make deferred split shrinker memcg aware"): which included a check on swapcache before adding to deferred queue, but no check on deferred queue before adding THP to swapcache. That worked fine with the usual sequence of events in reclaim (though there were a couple of rare ways in which a THP on deferred queue could have been swapped out), but 6.12 commitdafff3f4c8
("mm: split underused THPs") avoids splitting underused THPs in reclaim, which makes swapcache THPs on deferred queue commonplace. Keep the check on swapcache before adding to deferred queue? Yes: it is no longer essential, but preserves the existing behaviour, and is likely to be a worthwhile optimization (vmstat showed much more traffic on the queue under swapping load if the check was removed); update its comment. Memcg-v1 move (deprecated): mem_cgroup_move_account() has been changing folio->memcg_data without checking and unqueueing a THP folio from the deferred list, sometimes corrupting "from" memcg's list, like swapout. Refcount is non-zero here, so folio_unqueue_deferred_split() can only be used in a WARN_ON_ONCE to validate the fix, which must be done earlier: mem_cgroup_move_charge_pte_range() first try to split the THP (splitting of course unqueues), or skip it if that fails. Not ideal, but moving charge has been requested, and khugepaged should repair the THP later: nobody wants new custom unqueueing code just for this deprecated case. The87eaceb3fa
commit did have the code to move from one deferred list to another (but was not conscious of its unsafety while refcount non-0); but that was removed by 5.6 commitfac0516b55
("mm: thp: don't need care deferred split queue in memcg charge move path"), which argued that the existence of a PMD mapping guarantees that the THP cannot be on a deferred list. As above, false in rare cases, and now commonly false. Backport to 6.11 should be straightforward. Earlier backports must take care that other _deferred_list fixes and dependencies are included. There is not a strong case for backports, but they can fix cornercases. Link: https://lkml.kernel.org/r/8dc111ae-f6db-2da7-b25c-7a20b1effe3b@google.com Fixes:87eaceb3fa
("mm: thp: make deferred split shrinker memcg aware") Fixes:dafff3f4c8
("mm: split underused THPs") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Barry Song <baohua@kernel.org> Cc: Chris Li <chrisl@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Shakeel Butt <shakeel.butt@linux.dev> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
7605 lines
210 KiB
C
7605 lines
210 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*
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* Swap reorganised 29.12.95, Stephen Tweedie.
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* kswapd added: 7.1.96 sct
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* Removed kswapd_ctl limits, and swap out as many pages as needed
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* to bring the system back to freepages.high: 2.4.97, Rik van Riel.
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* Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
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* Multiqueue VM started 5.8.00, Rik van Riel.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/mm.h>
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#include <linux/sched/mm.h>
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#include <linux/module.h>
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#include <linux/gfp.h>
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#include <linux/kernel_stat.h>
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#include <linux/swap.h>
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#include <linux/pagemap.h>
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#include <linux/init.h>
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#include <linux/highmem.h>
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#include <linux/vmpressure.h>
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#include <linux/vmstat.h>
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#include <linux/file.h>
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#include <linux/writeback.h>
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#include <linux/blkdev.h>
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#include <linux/buffer_head.h> /* for buffer_heads_over_limit */
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#include <linux/mm_inline.h>
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#include <linux/backing-dev.h>
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#include <linux/rmap.h>
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#include <linux/topology.h>
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#include <linux/cpu.h>
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#include <linux/cpuset.h>
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#include <linux/compaction.h>
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#include <linux/notifier.h>
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#include <linux/delay.h>
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#include <linux/kthread.h>
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#include <linux/freezer.h>
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#include <linux/memcontrol.h>
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#include <linux/migrate.h>
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#include <linux/delayacct.h>
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#include <linux/sysctl.h>
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#include <linux/memory-tiers.h>
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#include <linux/oom.h>
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#include <linux/pagevec.h>
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#include <linux/prefetch.h>
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#include <linux/printk.h>
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#include <linux/dax.h>
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#include <linux/psi.h>
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#include <linux/pagewalk.h>
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#include <linux/shmem_fs.h>
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#include <linux/ctype.h>
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#include <linux/debugfs.h>
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#include <linux/khugepaged.h>
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#include <linux/rculist_nulls.h>
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#include <linux/random.h>
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#include <linux/mmu_notifier.h>
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#include <asm/tlbflush.h>
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#include <asm/div64.h>
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#include <linux/swapops.h>
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#include <linux/balloon_compaction.h>
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#include <linux/sched/sysctl.h>
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#include "internal.h"
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#include "swap.h"
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#define CREATE_TRACE_POINTS
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#include <trace/events/vmscan.h>
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struct scan_control {
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/* How many pages shrink_list() should reclaim */
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unsigned long nr_to_reclaim;
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/*
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* Nodemask of nodes allowed by the caller. If NULL, all nodes
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* are scanned.
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*/
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nodemask_t *nodemask;
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/*
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* The memory cgroup that hit its limit and as a result is the
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* primary target of this reclaim invocation.
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*/
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struct mem_cgroup *target_mem_cgroup;
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/*
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* Scan pressure balancing between anon and file LRUs
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*/
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unsigned long anon_cost;
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unsigned long file_cost;
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#ifdef CONFIG_MEMCG
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/* Swappiness value for proactive reclaim. Always use sc_swappiness()! */
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int *proactive_swappiness;
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#endif
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/* Can active folios be deactivated as part of reclaim? */
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#define DEACTIVATE_ANON 1
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#define DEACTIVATE_FILE 2
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unsigned int may_deactivate:2;
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unsigned int force_deactivate:1;
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unsigned int skipped_deactivate:1;
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/* Writepage batching in laptop mode; RECLAIM_WRITE */
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unsigned int may_writepage:1;
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/* Can mapped folios be reclaimed? */
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unsigned int may_unmap:1;
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|
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/* Can folios be swapped as part of reclaim? */
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unsigned int may_swap:1;
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/* Not allow cache_trim_mode to be turned on as part of reclaim? */
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unsigned int no_cache_trim_mode:1;
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/* Has cache_trim_mode failed at least once? */
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unsigned int cache_trim_mode_failed:1;
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/* Proactive reclaim invoked by userspace through memory.reclaim */
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unsigned int proactive:1;
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/*
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* Cgroup memory below memory.low is protected as long as we
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* don't threaten to OOM. If any cgroup is reclaimed at
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* reduced force or passed over entirely due to its memory.low
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* setting (memcg_low_skipped), and nothing is reclaimed as a
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* result, then go back for one more cycle that reclaims the protected
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* memory (memcg_low_reclaim) to avert OOM.
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*/
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unsigned int memcg_low_reclaim:1;
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unsigned int memcg_low_skipped:1;
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/* Shared cgroup tree walk failed, rescan the whole tree */
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unsigned int memcg_full_walk:1;
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unsigned int hibernation_mode:1;
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/* One of the zones is ready for compaction */
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unsigned int compaction_ready:1;
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/* There is easily reclaimable cold cache in the current node */
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unsigned int cache_trim_mode:1;
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/* The file folios on the current node are dangerously low */
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unsigned int file_is_tiny:1;
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/* Always discard instead of demoting to lower tier memory */
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unsigned int no_demotion:1;
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/* Allocation order */
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s8 order;
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/* Scan (total_size >> priority) pages at once */
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s8 priority;
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/* The highest zone to isolate folios for reclaim from */
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s8 reclaim_idx;
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/* This context's GFP mask */
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gfp_t gfp_mask;
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/* Incremented by the number of inactive pages that were scanned */
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unsigned long nr_scanned;
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/* Number of pages freed so far during a call to shrink_zones() */
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unsigned long nr_reclaimed;
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struct {
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unsigned int dirty;
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unsigned int unqueued_dirty;
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unsigned int congested;
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unsigned int writeback;
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unsigned int immediate;
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unsigned int file_taken;
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unsigned int taken;
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} nr;
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/* for recording the reclaimed slab by now */
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struct reclaim_state reclaim_state;
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};
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#ifdef ARCH_HAS_PREFETCHW
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#define prefetchw_prev_lru_folio(_folio, _base, _field) \
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do { \
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if ((_folio)->lru.prev != _base) { \
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struct folio *prev; \
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\
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prev = lru_to_folio(&(_folio->lru)); \
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prefetchw(&prev->_field); \
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} \
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} while (0)
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#else
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#define prefetchw_prev_lru_folio(_folio, _base, _field) do { } while (0)
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#endif
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/*
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* From 0 .. MAX_SWAPPINESS. Higher means more swappy.
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*/
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int vm_swappiness = 60;
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#ifdef CONFIG_MEMCG
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/* Returns true for reclaim through cgroup limits or cgroup interfaces. */
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static bool cgroup_reclaim(struct scan_control *sc)
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{
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return sc->target_mem_cgroup;
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}
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/*
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* Returns true for reclaim on the root cgroup. This is true for direct
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* allocator reclaim and reclaim through cgroup interfaces on the root cgroup.
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*/
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static bool root_reclaim(struct scan_control *sc)
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{
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return !sc->target_mem_cgroup || mem_cgroup_is_root(sc->target_mem_cgroup);
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}
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/**
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* writeback_throttling_sane - is the usual dirty throttling mechanism available?
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* @sc: scan_control in question
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*
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* The normal page dirty throttling mechanism in balance_dirty_pages() is
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* completely broken with the legacy memcg and direct stalling in
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* shrink_folio_list() is used for throttling instead, which lacks all the
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* niceties such as fairness, adaptive pausing, bandwidth proportional
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* allocation and configurability.
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*
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* This function tests whether the vmscan currently in progress can assume
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* that the normal dirty throttling mechanism is operational.
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*/
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static bool writeback_throttling_sane(struct scan_control *sc)
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{
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if (!cgroup_reclaim(sc))
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return true;
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#ifdef CONFIG_CGROUP_WRITEBACK
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if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
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return true;
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#endif
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return false;
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}
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static int sc_swappiness(struct scan_control *sc, struct mem_cgroup *memcg)
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{
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if (sc->proactive && sc->proactive_swappiness)
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return *sc->proactive_swappiness;
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return mem_cgroup_swappiness(memcg);
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}
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#else
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static bool cgroup_reclaim(struct scan_control *sc)
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{
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return false;
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}
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static bool root_reclaim(struct scan_control *sc)
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{
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return true;
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}
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static bool writeback_throttling_sane(struct scan_control *sc)
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{
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return true;
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}
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static int sc_swappiness(struct scan_control *sc, struct mem_cgroup *memcg)
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{
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return READ_ONCE(vm_swappiness);
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}
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#endif
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static void set_task_reclaim_state(struct task_struct *task,
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struct reclaim_state *rs)
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{
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/* Check for an overwrite */
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WARN_ON_ONCE(rs && task->reclaim_state);
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/* Check for the nulling of an already-nulled member */
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WARN_ON_ONCE(!rs && !task->reclaim_state);
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task->reclaim_state = rs;
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}
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/*
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* flush_reclaim_state(): add pages reclaimed outside of LRU-based reclaim to
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* scan_control->nr_reclaimed.
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*/
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static void flush_reclaim_state(struct scan_control *sc)
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{
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/*
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* Currently, reclaim_state->reclaimed includes three types of pages
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* freed outside of vmscan:
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* (1) Slab pages.
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* (2) Clean file pages from pruned inodes (on highmem systems).
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* (3) XFS freed buffer pages.
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*
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* For all of these cases, we cannot universally link the pages to a
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* single memcg. For example, a memcg-aware shrinker can free one object
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* charged to the target memcg, causing an entire page to be freed.
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* If we count the entire page as reclaimed from the memcg, we end up
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* overestimating the reclaimed amount (potentially under-reclaiming).
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*
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* Only count such pages for global reclaim to prevent under-reclaiming
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* from the target memcg; preventing unnecessary retries during memcg
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* charging and false positives from proactive reclaim.
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*
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* For uncommon cases where the freed pages were actually mostly
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* charged to the target memcg, we end up underestimating the reclaimed
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* amount. This should be fine. The freed pages will be uncharged
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* anyway, even if they are not counted here properly, and we will be
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* able to make forward progress in charging (which is usually in a
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* retry loop).
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*
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* We can go one step further, and report the uncharged objcg pages in
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* memcg reclaim, to make reporting more accurate and reduce
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* underestimation, but it's probably not worth the complexity for now.
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*/
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if (current->reclaim_state && root_reclaim(sc)) {
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sc->nr_reclaimed += current->reclaim_state->reclaimed;
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current->reclaim_state->reclaimed = 0;
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}
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}
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static bool can_demote(int nid, struct scan_control *sc)
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{
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if (!numa_demotion_enabled)
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return false;
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if (sc && sc->no_demotion)
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return false;
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if (next_demotion_node(nid) == NUMA_NO_NODE)
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return false;
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return true;
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}
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static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg,
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int nid,
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struct scan_control *sc)
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{
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if (memcg == NULL) {
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/*
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* For non-memcg reclaim, is there
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* space in any swap device?
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*/
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if (get_nr_swap_pages() > 0)
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return true;
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} else {
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/* Is the memcg below its swap limit? */
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if (mem_cgroup_get_nr_swap_pages(memcg) > 0)
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return true;
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}
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/*
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* The page can not be swapped.
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*
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* Can it be reclaimed from this node via demotion?
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*/
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return can_demote(nid, sc);
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}
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/*
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* This misses isolated folios which are not accounted for to save counters.
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* As the data only determines if reclaim or compaction continues, it is
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* not expected that isolated folios will be a dominating factor.
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*/
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unsigned long zone_reclaimable_pages(struct zone *zone)
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{
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unsigned long nr;
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nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) +
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zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE);
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if (can_reclaim_anon_pages(NULL, zone_to_nid(zone), NULL))
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nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) +
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zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON);
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return nr;
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}
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/**
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* lruvec_lru_size - Returns the number of pages on the given LRU list.
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* @lruvec: lru vector
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* @lru: lru to use
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* @zone_idx: zones to consider (use MAX_NR_ZONES - 1 for the whole LRU list)
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*/
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static unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru,
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int zone_idx)
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{
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unsigned long size = 0;
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int zid;
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for (zid = 0; zid <= zone_idx; zid++) {
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struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid];
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|
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if (!managed_zone(zone))
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continue;
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|
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if (!mem_cgroup_disabled())
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size += mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
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else
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size += zone_page_state(zone, NR_ZONE_LRU_BASE + lru);
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}
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return size;
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}
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|
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static unsigned long drop_slab_node(int nid)
|
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{
|
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unsigned long freed = 0;
|
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struct mem_cgroup *memcg = NULL;
|
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|
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memcg = mem_cgroup_iter(NULL, NULL, NULL);
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do {
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freed += shrink_slab(GFP_KERNEL, nid, memcg, 0);
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} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
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|
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return freed;
|
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}
|
||
|
||
void drop_slab(void)
|
||
{
|
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int nid;
|
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int shift = 0;
|
||
unsigned long freed;
|
||
|
||
do {
|
||
freed = 0;
|
||
for_each_online_node(nid) {
|
||
if (fatal_signal_pending(current))
|
||
return;
|
||
|
||
freed += drop_slab_node(nid);
|
||
}
|
||
} while ((freed >> shift++) > 1);
|
||
}
|
||
|
||
static int reclaimer_offset(void)
|
||
{
|
||
BUILD_BUG_ON(PGSTEAL_DIRECT - PGSTEAL_KSWAPD !=
|
||
PGDEMOTE_DIRECT - PGDEMOTE_KSWAPD);
|
||
BUILD_BUG_ON(PGSTEAL_KHUGEPAGED - PGSTEAL_KSWAPD !=
|
||
PGDEMOTE_KHUGEPAGED - PGDEMOTE_KSWAPD);
|
||
BUILD_BUG_ON(PGSTEAL_DIRECT - PGSTEAL_KSWAPD !=
|
||
PGSCAN_DIRECT - PGSCAN_KSWAPD);
|
||
BUILD_BUG_ON(PGSTEAL_KHUGEPAGED - PGSTEAL_KSWAPD !=
|
||
PGSCAN_KHUGEPAGED - PGSCAN_KSWAPD);
|
||
|
||
if (current_is_kswapd())
|
||
return 0;
|
||
if (current_is_khugepaged())
|
||
return PGSTEAL_KHUGEPAGED - PGSTEAL_KSWAPD;
|
||
return PGSTEAL_DIRECT - PGSTEAL_KSWAPD;
|
||
}
|
||
|
||
static inline int is_page_cache_freeable(struct folio *folio)
|
||
{
|
||
/*
|
||
* A freeable page cache folio is referenced only by the caller
|
||
* that isolated the folio, the page cache and optional filesystem
|
||
* private data at folio->private.
|
||
*/
|
||
return folio_ref_count(folio) - folio_test_private(folio) ==
|
||
1 + folio_nr_pages(folio);
|
||
}
|
||
|
||
/*
|
||
* We detected a synchronous write error writing a folio out. Probably
|
||
* -ENOSPC. We need to propagate that into the address_space for a subsequent
|
||
* fsync(), msync() or close().
|
||
*
|
||
* The tricky part is that after writepage we cannot touch the mapping: nothing
|
||
* prevents it from being freed up. But we have a ref on the folio and once
|
||
* that folio is locked, the mapping is pinned.
|
||
*
|
||
* We're allowed to run sleeping folio_lock() here because we know the caller has
|
||
* __GFP_FS.
|
||
*/
|
||
static void handle_write_error(struct address_space *mapping,
|
||
struct folio *folio, int error)
|
||
{
|
||
folio_lock(folio);
|
||
if (folio_mapping(folio) == mapping)
|
||
mapping_set_error(mapping, error);
|
||
folio_unlock(folio);
|
||
}
|
||
|
||
static bool skip_throttle_noprogress(pg_data_t *pgdat)
|
||
{
|
||
int reclaimable = 0, write_pending = 0;
|
||
int i;
|
||
|
||
/*
|
||
* If kswapd is disabled, reschedule if necessary but do not
|
||
* throttle as the system is likely near OOM.
|
||
*/
|
||
if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES)
|
||
return true;
|
||
|
||
/*
|
||
* If there are a lot of dirty/writeback folios then do not
|
||
* throttle as throttling will occur when the folios cycle
|
||
* towards the end of the LRU if still under writeback.
|
||
*/
|
||
for (i = 0; i < MAX_NR_ZONES; i++) {
|
||
struct zone *zone = pgdat->node_zones + i;
|
||
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
reclaimable += zone_reclaimable_pages(zone);
|
||
write_pending += zone_page_state_snapshot(zone,
|
||
NR_ZONE_WRITE_PENDING);
|
||
}
|
||
if (2 * write_pending <= reclaimable)
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason)
|
||
{
|
||
wait_queue_head_t *wqh = &pgdat->reclaim_wait[reason];
|
||
long timeout, ret;
|
||
DEFINE_WAIT(wait);
|
||
|
||
/*
|
||
* Do not throttle user workers, kthreads other than kswapd or
|
||
* workqueues. They may be required for reclaim to make
|
||
* forward progress (e.g. journalling workqueues or kthreads).
|
||
*/
|
||
if (!current_is_kswapd() &&
|
||
current->flags & (PF_USER_WORKER|PF_KTHREAD)) {
|
||
cond_resched();
|
||
return;
|
||
}
|
||
|
||
/*
|
||
* These figures are pulled out of thin air.
|
||
* VMSCAN_THROTTLE_ISOLATED is a transient condition based on too many
|
||
* parallel reclaimers which is a short-lived event so the timeout is
|
||
* short. Failing to make progress or waiting on writeback are
|
||
* potentially long-lived events so use a longer timeout. This is shaky
|
||
* logic as a failure to make progress could be due to anything from
|
||
* writeback to a slow device to excessive referenced folios at the tail
|
||
* of the inactive LRU.
|
||
*/
|
||
switch(reason) {
|
||
case VMSCAN_THROTTLE_WRITEBACK:
|
||
timeout = HZ/10;
|
||
|
||
if (atomic_inc_return(&pgdat->nr_writeback_throttled) == 1) {
|
||
WRITE_ONCE(pgdat->nr_reclaim_start,
|
||
node_page_state(pgdat, NR_THROTTLED_WRITTEN));
|
||
}
|
||
|
||
break;
|
||
case VMSCAN_THROTTLE_CONGESTED:
|
||
fallthrough;
|
||
case VMSCAN_THROTTLE_NOPROGRESS:
|
||
if (skip_throttle_noprogress(pgdat)) {
|
||
cond_resched();
|
||
return;
|
||
}
|
||
|
||
timeout = 1;
|
||
|
||
break;
|
||
case VMSCAN_THROTTLE_ISOLATED:
|
||
timeout = HZ/50;
|
||
break;
|
||
default:
|
||
WARN_ON_ONCE(1);
|
||
timeout = HZ;
|
||
break;
|
||
}
|
||
|
||
prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
|
||
ret = schedule_timeout(timeout);
|
||
finish_wait(wqh, &wait);
|
||
|
||
if (reason == VMSCAN_THROTTLE_WRITEBACK)
|
||
atomic_dec(&pgdat->nr_writeback_throttled);
|
||
|
||
trace_mm_vmscan_throttled(pgdat->node_id, jiffies_to_usecs(timeout),
|
||
jiffies_to_usecs(timeout - ret),
|
||
reason);
|
||
}
|
||
|
||
/*
|
||
* Account for folios written if tasks are throttled waiting on dirty
|
||
* folios to clean. If enough folios have been cleaned since throttling
|
||
* started then wakeup the throttled tasks.
|
||
*/
|
||
void __acct_reclaim_writeback(pg_data_t *pgdat, struct folio *folio,
|
||
int nr_throttled)
|
||
{
|
||
unsigned long nr_written;
|
||
|
||
node_stat_add_folio(folio, NR_THROTTLED_WRITTEN);
|
||
|
||
/*
|
||
* This is an inaccurate read as the per-cpu deltas may not
|
||
* be synchronised. However, given that the system is
|
||
* writeback throttled, it is not worth taking the penalty
|
||
* of getting an accurate count. At worst, the throttle
|
||
* timeout guarantees forward progress.
|
||
*/
|
||
nr_written = node_page_state(pgdat, NR_THROTTLED_WRITTEN) -
|
||
READ_ONCE(pgdat->nr_reclaim_start);
|
||
|
||
if (nr_written > SWAP_CLUSTER_MAX * nr_throttled)
|
||
wake_up(&pgdat->reclaim_wait[VMSCAN_THROTTLE_WRITEBACK]);
|
||
}
|
||
|
||
/* possible outcome of pageout() */
|
||
typedef enum {
|
||
/* failed to write folio out, folio is locked */
|
||
PAGE_KEEP,
|
||
/* move folio to the active list, folio is locked */
|
||
PAGE_ACTIVATE,
|
||
/* folio has been sent to the disk successfully, folio is unlocked */
|
||
PAGE_SUCCESS,
|
||
/* folio is clean and locked */
|
||
PAGE_CLEAN,
|
||
} pageout_t;
|
||
|
||
/*
|
||
* pageout is called by shrink_folio_list() for each dirty folio.
|
||
* Calls ->writepage().
|
||
*/
|
||
static pageout_t pageout(struct folio *folio, struct address_space *mapping,
|
||
struct swap_iocb **plug, struct list_head *folio_list)
|
||
{
|
||
/*
|
||
* If the folio is dirty, only perform writeback if that write
|
||
* will be non-blocking. To prevent this allocation from being
|
||
* stalled by pagecache activity. But note that there may be
|
||
* stalls if we need to run get_block(). We could test
|
||
* PagePrivate for that.
|
||
*
|
||
* If this process is currently in __generic_file_write_iter() against
|
||
* this folio's queue, we can perform writeback even if that
|
||
* will block.
|
||
*
|
||
* If the folio is swapcache, write it back even if that would
|
||
* block, for some throttling. This happens by accident, because
|
||
* swap_backing_dev_info is bust: it doesn't reflect the
|
||
* congestion state of the swapdevs. Easy to fix, if needed.
|
||
*/
|
||
if (!is_page_cache_freeable(folio))
|
||
return PAGE_KEEP;
|
||
if (!mapping) {
|
||
/*
|
||
* Some data journaling orphaned folios can have
|
||
* folio->mapping == NULL while being dirty with clean buffers.
|
||
*/
|
||
if (folio_test_private(folio)) {
|
||
if (try_to_free_buffers(folio)) {
|
||
folio_clear_dirty(folio);
|
||
pr_info("%s: orphaned folio\n", __func__);
|
||
return PAGE_CLEAN;
|
||
}
|
||
}
|
||
return PAGE_KEEP;
|
||
}
|
||
if (mapping->a_ops->writepage == NULL)
|
||
return PAGE_ACTIVATE;
|
||
|
||
if (folio_clear_dirty_for_io(folio)) {
|
||
int res;
|
||
struct writeback_control wbc = {
|
||
.sync_mode = WB_SYNC_NONE,
|
||
.nr_to_write = SWAP_CLUSTER_MAX,
|
||
.range_start = 0,
|
||
.range_end = LLONG_MAX,
|
||
.for_reclaim = 1,
|
||
.swap_plug = plug,
|
||
};
|
||
|
||
/*
|
||
* The large shmem folio can be split if CONFIG_THP_SWAP is
|
||
* not enabled or contiguous swap entries are failed to
|
||
* allocate.
|
||
*/
|
||
if (shmem_mapping(mapping) && folio_test_large(folio))
|
||
wbc.list = folio_list;
|
||
|
||
folio_set_reclaim(folio);
|
||
res = mapping->a_ops->writepage(&folio->page, &wbc);
|
||
if (res < 0)
|
||
handle_write_error(mapping, folio, res);
|
||
if (res == AOP_WRITEPAGE_ACTIVATE) {
|
||
folio_clear_reclaim(folio);
|
||
return PAGE_ACTIVATE;
|
||
}
|
||
|
||
if (!folio_test_writeback(folio)) {
|
||
/* synchronous write or broken a_ops? */
|
||
folio_clear_reclaim(folio);
|
||
}
|
||
trace_mm_vmscan_write_folio(folio);
|
||
node_stat_add_folio(folio, NR_VMSCAN_WRITE);
|
||
return PAGE_SUCCESS;
|
||
}
|
||
|
||
return PAGE_CLEAN;
|
||
}
|
||
|
||
/*
|
||
* Same as remove_mapping, but if the folio is removed from the mapping, it
|
||
* gets returned with a refcount of 0.
|
||
*/
|
||
static int __remove_mapping(struct address_space *mapping, struct folio *folio,
|
||
bool reclaimed, struct mem_cgroup *target_memcg)
|
||
{
|
||
int refcount;
|
||
void *shadow = NULL;
|
||
|
||
BUG_ON(!folio_test_locked(folio));
|
||
BUG_ON(mapping != folio_mapping(folio));
|
||
|
||
if (!folio_test_swapcache(folio))
|
||
spin_lock(&mapping->host->i_lock);
|
||
xa_lock_irq(&mapping->i_pages);
|
||
/*
|
||
* The non racy check for a busy folio.
|
||
*
|
||
* Must be careful with the order of the tests. When someone has
|
||
* a ref to the folio, it may be possible that they dirty it then
|
||
* drop the reference. So if the dirty flag is tested before the
|
||
* refcount here, then the following race may occur:
|
||
*
|
||
* get_user_pages(&page);
|
||
* [user mapping goes away]
|
||
* write_to(page);
|
||
* !folio_test_dirty(folio) [good]
|
||
* folio_set_dirty(folio);
|
||
* folio_put(folio);
|
||
* !refcount(folio) [good, discard it]
|
||
*
|
||
* [oops, our write_to data is lost]
|
||
*
|
||
* Reversing the order of the tests ensures such a situation cannot
|
||
* escape unnoticed. The smp_rmb is needed to ensure the folio->flags
|
||
* load is not satisfied before that of folio->_refcount.
|
||
*
|
||
* Note that if the dirty flag is always set via folio_mark_dirty,
|
||
* and thus under the i_pages lock, then this ordering is not required.
|
||
*/
|
||
refcount = 1 + folio_nr_pages(folio);
|
||
if (!folio_ref_freeze(folio, refcount))
|
||
goto cannot_free;
|
||
/* note: atomic_cmpxchg in folio_ref_freeze provides the smp_rmb */
|
||
if (unlikely(folio_test_dirty(folio))) {
|
||
folio_ref_unfreeze(folio, refcount);
|
||
goto cannot_free;
|
||
}
|
||
|
||
if (folio_test_swapcache(folio)) {
|
||
swp_entry_t swap = folio->swap;
|
||
|
||
if (reclaimed && !mapping_exiting(mapping))
|
||
shadow = workingset_eviction(folio, target_memcg);
|
||
__delete_from_swap_cache(folio, swap, shadow);
|
||
mem_cgroup_swapout(folio, swap);
|
||
xa_unlock_irq(&mapping->i_pages);
|
||
put_swap_folio(folio, swap);
|
||
} else {
|
||
void (*free_folio)(struct folio *);
|
||
|
||
free_folio = mapping->a_ops->free_folio;
|
||
/*
|
||
* Remember a shadow entry for reclaimed file cache in
|
||
* order to detect refaults, thus thrashing, later on.
|
||
*
|
||
* But don't store shadows in an address space that is
|
||
* already exiting. This is not just an optimization,
|
||
* inode reclaim needs to empty out the radix tree or
|
||
* the nodes are lost. Don't plant shadows behind its
|
||
* back.
|
||
*
|
||
* We also don't store shadows for DAX mappings because the
|
||
* only page cache folios found in these are zero pages
|
||
* covering holes, and because we don't want to mix DAX
|
||
* exceptional entries and shadow exceptional entries in the
|
||
* same address_space.
|
||
*/
|
||
if (reclaimed && folio_is_file_lru(folio) &&
|
||
!mapping_exiting(mapping) && !dax_mapping(mapping))
|
||
shadow = workingset_eviction(folio, target_memcg);
|
||
__filemap_remove_folio(folio, shadow);
|
||
xa_unlock_irq(&mapping->i_pages);
|
||
if (mapping_shrinkable(mapping))
|
||
inode_add_lru(mapping->host);
|
||
spin_unlock(&mapping->host->i_lock);
|
||
|
||
if (free_folio)
|
||
free_folio(folio);
|
||
}
|
||
|
||
return 1;
|
||
|
||
cannot_free:
|
||
xa_unlock_irq(&mapping->i_pages);
|
||
if (!folio_test_swapcache(folio))
|
||
spin_unlock(&mapping->host->i_lock);
|
||
return 0;
|
||
}
|
||
|
||
/**
|
||
* remove_mapping() - Attempt to remove a folio from its mapping.
|
||
* @mapping: The address space.
|
||
* @folio: The folio to remove.
|
||
*
|
||
* If the folio is dirty, under writeback or if someone else has a ref
|
||
* on it, removal will fail.
|
||
* Return: The number of pages removed from the mapping. 0 if the folio
|
||
* could not be removed.
|
||
* Context: The caller should have a single refcount on the folio and
|
||
* hold its lock.
|
||
*/
|
||
long remove_mapping(struct address_space *mapping, struct folio *folio)
|
||
{
|
||
if (__remove_mapping(mapping, folio, false, NULL)) {
|
||
/*
|
||
* Unfreezing the refcount with 1 effectively
|
||
* drops the pagecache ref for us without requiring another
|
||
* atomic operation.
|
||
*/
|
||
folio_ref_unfreeze(folio, 1);
|
||
return folio_nr_pages(folio);
|
||
}
|
||
return 0;
|
||
}
|
||
|
||
/**
|
||
* folio_putback_lru - Put previously isolated folio onto appropriate LRU list.
|
||
* @folio: Folio to be returned to an LRU list.
|
||
*
|
||
* Add previously isolated @folio to appropriate LRU list.
|
||
* The folio may still be unevictable for other reasons.
|
||
*
|
||
* Context: lru_lock must not be held, interrupts must be enabled.
|
||
*/
|
||
void folio_putback_lru(struct folio *folio)
|
||
{
|
||
folio_add_lru(folio);
|
||
folio_put(folio); /* drop ref from isolate */
|
||
}
|
||
|
||
enum folio_references {
|
||
FOLIOREF_RECLAIM,
|
||
FOLIOREF_RECLAIM_CLEAN,
|
||
FOLIOREF_KEEP,
|
||
FOLIOREF_ACTIVATE,
|
||
};
|
||
|
||
static enum folio_references folio_check_references(struct folio *folio,
|
||
struct scan_control *sc)
|
||
{
|
||
int referenced_ptes, referenced_folio;
|
||
unsigned long vm_flags;
|
||
|
||
referenced_ptes = folio_referenced(folio, 1, sc->target_mem_cgroup,
|
||
&vm_flags);
|
||
referenced_folio = folio_test_clear_referenced(folio);
|
||
|
||
/*
|
||
* The supposedly reclaimable folio was found to be in a VM_LOCKED vma.
|
||
* Let the folio, now marked Mlocked, be moved to the unevictable list.
|
||
*/
|
||
if (vm_flags & VM_LOCKED)
|
||
return FOLIOREF_ACTIVATE;
|
||
|
||
/*
|
||
* There are two cases to consider.
|
||
* 1) Rmap lock contention: rotate.
|
||
* 2) Skip the non-shared swapbacked folio mapped solely by
|
||
* the exiting or OOM-reaped process.
|
||
*/
|
||
if (referenced_ptes == -1)
|
||
return FOLIOREF_KEEP;
|
||
|
||
if (referenced_ptes) {
|
||
/*
|
||
* All mapped folios start out with page table
|
||
* references from the instantiating fault, so we need
|
||
* to look twice if a mapped file/anon folio is used more
|
||
* than once.
|
||
*
|
||
* Mark it and spare it for another trip around the
|
||
* inactive list. Another page table reference will
|
||
* lead to its activation.
|
||
*
|
||
* Note: the mark is set for activated folios as well
|
||
* so that recently deactivated but used folios are
|
||
* quickly recovered.
|
||
*/
|
||
folio_set_referenced(folio);
|
||
|
||
if (referenced_folio || referenced_ptes > 1)
|
||
return FOLIOREF_ACTIVATE;
|
||
|
||
/*
|
||
* Activate file-backed executable folios after first usage.
|
||
*/
|
||
if ((vm_flags & VM_EXEC) && folio_is_file_lru(folio))
|
||
return FOLIOREF_ACTIVATE;
|
||
|
||
return FOLIOREF_KEEP;
|
||
}
|
||
|
||
/* Reclaim if clean, defer dirty folios to writeback */
|
||
if (referenced_folio && folio_is_file_lru(folio))
|
||
return FOLIOREF_RECLAIM_CLEAN;
|
||
|
||
return FOLIOREF_RECLAIM;
|
||
}
|
||
|
||
/* Check if a folio is dirty or under writeback */
|
||
static void folio_check_dirty_writeback(struct folio *folio,
|
||
bool *dirty, bool *writeback)
|
||
{
|
||
struct address_space *mapping;
|
||
|
||
/*
|
||
* Anonymous folios are not handled by flushers and must be written
|
||
* from reclaim context. Do not stall reclaim based on them.
|
||
* MADV_FREE anonymous folios are put into inactive file list too.
|
||
* They could be mistakenly treated as file lru. So further anon
|
||
* test is needed.
|
||
*/
|
||
if (!folio_is_file_lru(folio) ||
|
||
(folio_test_anon(folio) && !folio_test_swapbacked(folio))) {
|
||
*dirty = false;
|
||
*writeback = false;
|
||
return;
|
||
}
|
||
|
||
/* By default assume that the folio flags are accurate */
|
||
*dirty = folio_test_dirty(folio);
|
||
*writeback = folio_test_writeback(folio);
|
||
|
||
/* Verify dirty/writeback state if the filesystem supports it */
|
||
if (!folio_test_private(folio))
|
||
return;
|
||
|
||
mapping = folio_mapping(folio);
|
||
if (mapping && mapping->a_ops->is_dirty_writeback)
|
||
mapping->a_ops->is_dirty_writeback(folio, dirty, writeback);
|
||
}
|
||
|
||
struct folio *alloc_migrate_folio(struct folio *src, unsigned long private)
|
||
{
|
||
struct folio *dst;
|
||
nodemask_t *allowed_mask;
|
||
struct migration_target_control *mtc;
|
||
|
||
mtc = (struct migration_target_control *)private;
|
||
|
||
allowed_mask = mtc->nmask;
|
||
/*
|
||
* make sure we allocate from the target node first also trying to
|
||
* demote or reclaim pages from the target node via kswapd if we are
|
||
* low on free memory on target node. If we don't do this and if
|
||
* we have free memory on the slower(lower) memtier, we would start
|
||
* allocating pages from slower(lower) memory tiers without even forcing
|
||
* a demotion of cold pages from the target memtier. This can result
|
||
* in the kernel placing hot pages in slower(lower) memory tiers.
|
||
*/
|
||
mtc->nmask = NULL;
|
||
mtc->gfp_mask |= __GFP_THISNODE;
|
||
dst = alloc_migration_target(src, (unsigned long)mtc);
|
||
if (dst)
|
||
return dst;
|
||
|
||
mtc->gfp_mask &= ~__GFP_THISNODE;
|
||
mtc->nmask = allowed_mask;
|
||
|
||
return alloc_migration_target(src, (unsigned long)mtc);
|
||
}
|
||
|
||
/*
|
||
* Take folios on @demote_folios and attempt to demote them to another node.
|
||
* Folios which are not demoted are left on @demote_folios.
|
||
*/
|
||
static unsigned int demote_folio_list(struct list_head *demote_folios,
|
||
struct pglist_data *pgdat)
|
||
{
|
||
int target_nid = next_demotion_node(pgdat->node_id);
|
||
unsigned int nr_succeeded;
|
||
nodemask_t allowed_mask;
|
||
|
||
struct migration_target_control mtc = {
|
||
/*
|
||
* Allocate from 'node', or fail quickly and quietly.
|
||
* When this happens, 'page' will likely just be discarded
|
||
* instead of migrated.
|
||
*/
|
||
.gfp_mask = (GFP_HIGHUSER_MOVABLE & ~__GFP_RECLAIM) | __GFP_NOWARN |
|
||
__GFP_NOMEMALLOC | GFP_NOWAIT,
|
||
.nid = target_nid,
|
||
.nmask = &allowed_mask,
|
||
.reason = MR_DEMOTION,
|
||
};
|
||
|
||
if (list_empty(demote_folios))
|
||
return 0;
|
||
|
||
if (target_nid == NUMA_NO_NODE)
|
||
return 0;
|
||
|
||
node_get_allowed_targets(pgdat, &allowed_mask);
|
||
|
||
/* Demotion ignores all cpuset and mempolicy settings */
|
||
migrate_pages(demote_folios, alloc_migrate_folio, NULL,
|
||
(unsigned long)&mtc, MIGRATE_ASYNC, MR_DEMOTION,
|
||
&nr_succeeded);
|
||
|
||
return nr_succeeded;
|
||
}
|
||
|
||
static bool may_enter_fs(struct folio *folio, gfp_t gfp_mask)
|
||
{
|
||
if (gfp_mask & __GFP_FS)
|
||
return true;
|
||
if (!folio_test_swapcache(folio) || !(gfp_mask & __GFP_IO))
|
||
return false;
|
||
/*
|
||
* We can "enter_fs" for swap-cache with only __GFP_IO
|
||
* providing this isn't SWP_FS_OPS.
|
||
* ->flags can be updated non-atomicially (scan_swap_map_slots),
|
||
* but that will never affect SWP_FS_OPS, so the data_race
|
||
* is safe.
|
||
*/
|
||
return !data_race(folio_swap_flags(folio) & SWP_FS_OPS);
|
||
}
|
||
|
||
/*
|
||
* shrink_folio_list() returns the number of reclaimed pages
|
||
*/
|
||
static unsigned int shrink_folio_list(struct list_head *folio_list,
|
||
struct pglist_data *pgdat, struct scan_control *sc,
|
||
struct reclaim_stat *stat, bool ignore_references)
|
||
{
|
||
struct folio_batch free_folios;
|
||
LIST_HEAD(ret_folios);
|
||
LIST_HEAD(demote_folios);
|
||
unsigned int nr_reclaimed = 0;
|
||
unsigned int pgactivate = 0;
|
||
bool do_demote_pass;
|
||
struct swap_iocb *plug = NULL;
|
||
|
||
folio_batch_init(&free_folios);
|
||
memset(stat, 0, sizeof(*stat));
|
||
cond_resched();
|
||
do_demote_pass = can_demote(pgdat->node_id, sc);
|
||
|
||
retry:
|
||
while (!list_empty(folio_list)) {
|
||
struct address_space *mapping;
|
||
struct folio *folio;
|
||
enum folio_references references = FOLIOREF_RECLAIM;
|
||
bool dirty, writeback;
|
||
unsigned int nr_pages;
|
||
|
||
cond_resched();
|
||
|
||
folio = lru_to_folio(folio_list);
|
||
list_del(&folio->lru);
|
||
|
||
if (!folio_trylock(folio))
|
||
goto keep;
|
||
|
||
VM_BUG_ON_FOLIO(folio_test_active(folio), folio);
|
||
|
||
nr_pages = folio_nr_pages(folio);
|
||
|
||
/* Account the number of base pages */
|
||
sc->nr_scanned += nr_pages;
|
||
|
||
if (unlikely(!folio_evictable(folio)))
|
||
goto activate_locked;
|
||
|
||
if (!sc->may_unmap && folio_mapped(folio))
|
||
goto keep_locked;
|
||
|
||
/* folio_update_gen() tried to promote this page? */
|
||
if (lru_gen_enabled() && !ignore_references &&
|
||
folio_mapped(folio) && folio_test_referenced(folio))
|
||
goto keep_locked;
|
||
|
||
/*
|
||
* The number of dirty pages determines if a node is marked
|
||
* reclaim_congested. kswapd will stall and start writing
|
||
* folios if the tail of the LRU is all dirty unqueued folios.
|
||
*/
|
||
folio_check_dirty_writeback(folio, &dirty, &writeback);
|
||
if (dirty || writeback)
|
||
stat->nr_dirty += nr_pages;
|
||
|
||
if (dirty && !writeback)
|
||
stat->nr_unqueued_dirty += nr_pages;
|
||
|
||
/*
|
||
* Treat this folio as congested if folios are cycling
|
||
* through the LRU so quickly that the folios marked
|
||
* for immediate reclaim are making it to the end of
|
||
* the LRU a second time.
|
||
*/
|
||
if (writeback && folio_test_reclaim(folio))
|
||
stat->nr_congested += nr_pages;
|
||
|
||
/*
|
||
* If a folio at the tail of the LRU is under writeback, there
|
||
* are three cases to consider.
|
||
*
|
||
* 1) If reclaim is encountering an excessive number
|
||
* of folios under writeback and this folio has both
|
||
* the writeback and reclaim flags set, then it
|
||
* indicates that folios are being queued for I/O but
|
||
* are being recycled through the LRU before the I/O
|
||
* can complete. Waiting on the folio itself risks an
|
||
* indefinite stall if it is impossible to writeback
|
||
* the folio due to I/O error or disconnected storage
|
||
* so instead note that the LRU is being scanned too
|
||
* quickly and the caller can stall after the folio
|
||
* list has been processed.
|
||
*
|
||
* 2) Global or new memcg reclaim encounters a folio that is
|
||
* not marked for immediate reclaim, or the caller does not
|
||
* have __GFP_FS (or __GFP_IO if it's simply going to swap,
|
||
* not to fs). In this case mark the folio for immediate
|
||
* reclaim and continue scanning.
|
||
*
|
||
* Require may_enter_fs() because we would wait on fs, which
|
||
* may not have submitted I/O yet. And the loop driver might
|
||
* enter reclaim, and deadlock if it waits on a folio for
|
||
* which it is needed to do the write (loop masks off
|
||
* __GFP_IO|__GFP_FS for this reason); but more thought
|
||
* would probably show more reasons.
|
||
*
|
||
* 3) Legacy memcg encounters a folio that already has the
|
||
* reclaim flag set. memcg does not have any dirty folio
|
||
* throttling so we could easily OOM just because too many
|
||
* folios are in writeback and there is nothing else to
|
||
* reclaim. Wait for the writeback to complete.
|
||
*
|
||
* In cases 1) and 2) we activate the folios to get them out of
|
||
* the way while we continue scanning for clean folios on the
|
||
* inactive list and refilling from the active list. The
|
||
* observation here is that waiting for disk writes is more
|
||
* expensive than potentially causing reloads down the line.
|
||
* Since they're marked for immediate reclaim, they won't put
|
||
* memory pressure on the cache working set any longer than it
|
||
* takes to write them to disk.
|
||
*/
|
||
if (folio_test_writeback(folio)) {
|
||
/* Case 1 above */
|
||
if (current_is_kswapd() &&
|
||
folio_test_reclaim(folio) &&
|
||
test_bit(PGDAT_WRITEBACK, &pgdat->flags)) {
|
||
stat->nr_immediate += nr_pages;
|
||
goto activate_locked;
|
||
|
||
/* Case 2 above */
|
||
} else if (writeback_throttling_sane(sc) ||
|
||
!folio_test_reclaim(folio) ||
|
||
!may_enter_fs(folio, sc->gfp_mask)) {
|
||
/*
|
||
* This is slightly racy -
|
||
* folio_end_writeback() might have
|
||
* just cleared the reclaim flag, then
|
||
* setting the reclaim flag here ends up
|
||
* interpreted as the readahead flag - but
|
||
* that does not matter enough to care.
|
||
* What we do want is for this folio to
|
||
* have the reclaim flag set next time
|
||
* memcg reclaim reaches the tests above,
|
||
* so it will then wait for writeback to
|
||
* avoid OOM; and it's also appropriate
|
||
* in global reclaim.
|
||
*/
|
||
folio_set_reclaim(folio);
|
||
stat->nr_writeback += nr_pages;
|
||
goto activate_locked;
|
||
|
||
/* Case 3 above */
|
||
} else {
|
||
folio_unlock(folio);
|
||
folio_wait_writeback(folio);
|
||
/* then go back and try same folio again */
|
||
list_add_tail(&folio->lru, folio_list);
|
||
continue;
|
||
}
|
||
}
|
||
|
||
if (!ignore_references)
|
||
references = folio_check_references(folio, sc);
|
||
|
||
switch (references) {
|
||
case FOLIOREF_ACTIVATE:
|
||
goto activate_locked;
|
||
case FOLIOREF_KEEP:
|
||
stat->nr_ref_keep += nr_pages;
|
||
goto keep_locked;
|
||
case FOLIOREF_RECLAIM:
|
||
case FOLIOREF_RECLAIM_CLEAN:
|
||
; /* try to reclaim the folio below */
|
||
}
|
||
|
||
/*
|
||
* Before reclaiming the folio, try to relocate
|
||
* its contents to another node.
|
||
*/
|
||
if (do_demote_pass &&
|
||
(thp_migration_supported() || !folio_test_large(folio))) {
|
||
list_add(&folio->lru, &demote_folios);
|
||
folio_unlock(folio);
|
||
continue;
|
||
}
|
||
|
||
/*
|
||
* Anonymous process memory has backing store?
|
||
* Try to allocate it some swap space here.
|
||
* Lazyfree folio could be freed directly
|
||
*/
|
||
if (folio_test_anon(folio) && folio_test_swapbacked(folio)) {
|
||
if (!folio_test_swapcache(folio)) {
|
||
if (!(sc->gfp_mask & __GFP_IO))
|
||
goto keep_locked;
|
||
if (folio_maybe_dma_pinned(folio))
|
||
goto keep_locked;
|
||
if (folio_test_large(folio)) {
|
||
/* cannot split folio, skip it */
|
||
if (!can_split_folio(folio, 1, NULL))
|
||
goto activate_locked;
|
||
/*
|
||
* Split partially mapped folios right away.
|
||
* We can free the unmapped pages without IO.
|
||
*/
|
||
if (data_race(!list_empty(&folio->_deferred_list) &&
|
||
folio_test_partially_mapped(folio)) &&
|
||
split_folio_to_list(folio, folio_list))
|
||
goto activate_locked;
|
||
}
|
||
if (!add_to_swap(folio)) {
|
||
int __maybe_unused order = folio_order(folio);
|
||
|
||
if (!folio_test_large(folio))
|
||
goto activate_locked_split;
|
||
/* Fallback to swap normal pages */
|
||
if (split_folio_to_list(folio, folio_list))
|
||
goto activate_locked;
|
||
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
||
if (nr_pages >= HPAGE_PMD_NR) {
|
||
count_memcg_folio_events(folio,
|
||
THP_SWPOUT_FALLBACK, 1);
|
||
count_vm_event(THP_SWPOUT_FALLBACK);
|
||
}
|
||
count_mthp_stat(order, MTHP_STAT_SWPOUT_FALLBACK);
|
||
#endif
|
||
if (!add_to_swap(folio))
|
||
goto activate_locked_split;
|
||
}
|
||
}
|
||
}
|
||
|
||
/*
|
||
* If the folio was split above, the tail pages will make
|
||
* their own pass through this function and be accounted
|
||
* then.
|
||
*/
|
||
if ((nr_pages > 1) && !folio_test_large(folio)) {
|
||
sc->nr_scanned -= (nr_pages - 1);
|
||
nr_pages = 1;
|
||
}
|
||
|
||
/*
|
||
* The folio is mapped into the page tables of one or more
|
||
* processes. Try to unmap it here.
|
||
*/
|
||
if (folio_mapped(folio)) {
|
||
enum ttu_flags flags = TTU_BATCH_FLUSH;
|
||
bool was_swapbacked = folio_test_swapbacked(folio);
|
||
|
||
if (folio_test_pmd_mappable(folio))
|
||
flags |= TTU_SPLIT_HUGE_PMD;
|
||
/*
|
||
* Without TTU_SYNC, try_to_unmap will only begin to
|
||
* hold PTL from the first present PTE within a large
|
||
* folio. Some initial PTEs might be skipped due to
|
||
* races with parallel PTE writes in which PTEs can be
|
||
* cleared temporarily before being written new present
|
||
* values. This will lead to a large folio is still
|
||
* mapped while some subpages have been partially
|
||
* unmapped after try_to_unmap; TTU_SYNC helps
|
||
* try_to_unmap acquire PTL from the first PTE,
|
||
* eliminating the influence of temporary PTE values.
|
||
*/
|
||
if (folio_test_large(folio))
|
||
flags |= TTU_SYNC;
|
||
|
||
try_to_unmap(folio, flags);
|
||
if (folio_mapped(folio)) {
|
||
stat->nr_unmap_fail += nr_pages;
|
||
if (!was_swapbacked &&
|
||
folio_test_swapbacked(folio))
|
||
stat->nr_lazyfree_fail += nr_pages;
|
||
goto activate_locked;
|
||
}
|
||
}
|
||
|
||
/*
|
||
* Folio is unmapped now so it cannot be newly pinned anymore.
|
||
* No point in trying to reclaim folio if it is pinned.
|
||
* Furthermore we don't want to reclaim underlying fs metadata
|
||
* if the folio is pinned and thus potentially modified by the
|
||
* pinning process as that may upset the filesystem.
|
||
*/
|
||
if (folio_maybe_dma_pinned(folio))
|
||
goto activate_locked;
|
||
|
||
mapping = folio_mapping(folio);
|
||
if (folio_test_dirty(folio)) {
|
||
/*
|
||
* Only kswapd can writeback filesystem folios
|
||
* to avoid risk of stack overflow. But avoid
|
||
* injecting inefficient single-folio I/O into
|
||
* flusher writeback as much as possible: only
|
||
* write folios when we've encountered many
|
||
* dirty folios, and when we've already scanned
|
||
* the rest of the LRU for clean folios and see
|
||
* the same dirty folios again (with the reclaim
|
||
* flag set).
|
||
*/
|
||
if (folio_is_file_lru(folio) &&
|
||
(!current_is_kswapd() ||
|
||
!folio_test_reclaim(folio) ||
|
||
!test_bit(PGDAT_DIRTY, &pgdat->flags))) {
|
||
/*
|
||
* Immediately reclaim when written back.
|
||
* Similar in principle to folio_deactivate()
|
||
* except we already have the folio isolated
|
||
* and know it's dirty
|
||
*/
|
||
node_stat_mod_folio(folio, NR_VMSCAN_IMMEDIATE,
|
||
nr_pages);
|
||
folio_set_reclaim(folio);
|
||
|
||
goto activate_locked;
|
||
}
|
||
|
||
if (references == FOLIOREF_RECLAIM_CLEAN)
|
||
goto keep_locked;
|
||
if (!may_enter_fs(folio, sc->gfp_mask))
|
||
goto keep_locked;
|
||
if (!sc->may_writepage)
|
||
goto keep_locked;
|
||
|
||
/*
|
||
* Folio is dirty. Flush the TLB if a writable entry
|
||
* potentially exists to avoid CPU writes after I/O
|
||
* starts and then write it out here.
|
||
*/
|
||
try_to_unmap_flush_dirty();
|
||
switch (pageout(folio, mapping, &plug, folio_list)) {
|
||
case PAGE_KEEP:
|
||
goto keep_locked;
|
||
case PAGE_ACTIVATE:
|
||
/*
|
||
* If shmem folio is split when writeback to swap,
|
||
* the tail pages will make their own pass through
|
||
* this function and be accounted then.
|
||
*/
|
||
if (nr_pages > 1 && !folio_test_large(folio)) {
|
||
sc->nr_scanned -= (nr_pages - 1);
|
||
nr_pages = 1;
|
||
}
|
||
goto activate_locked;
|
||
case PAGE_SUCCESS:
|
||
if (nr_pages > 1 && !folio_test_large(folio)) {
|
||
sc->nr_scanned -= (nr_pages - 1);
|
||
nr_pages = 1;
|
||
}
|
||
stat->nr_pageout += nr_pages;
|
||
|
||
if (folio_test_writeback(folio))
|
||
goto keep;
|
||
if (folio_test_dirty(folio))
|
||
goto keep;
|
||
|
||
/*
|
||
* A synchronous write - probably a ramdisk. Go
|
||
* ahead and try to reclaim the folio.
|
||
*/
|
||
if (!folio_trylock(folio))
|
||
goto keep;
|
||
if (folio_test_dirty(folio) ||
|
||
folio_test_writeback(folio))
|
||
goto keep_locked;
|
||
mapping = folio_mapping(folio);
|
||
fallthrough;
|
||
case PAGE_CLEAN:
|
||
; /* try to free the folio below */
|
||
}
|
||
}
|
||
|
||
/*
|
||
* If the folio has buffers, try to free the buffer
|
||
* mappings associated with this folio. If we succeed
|
||
* we try to free the folio as well.
|
||
*
|
||
* We do this even if the folio is dirty.
|
||
* filemap_release_folio() does not perform I/O, but it
|
||
* is possible for a folio to have the dirty flag set,
|
||
* but it is actually clean (all its buffers are clean).
|
||
* This happens if the buffers were written out directly,
|
||
* with submit_bh(). ext3 will do this, as well as
|
||
* the blockdev mapping. filemap_release_folio() will
|
||
* discover that cleanness and will drop the buffers
|
||
* and mark the folio clean - it can be freed.
|
||
*
|
||
* Rarely, folios can have buffers and no ->mapping.
|
||
* These are the folios which were not successfully
|
||
* invalidated in truncate_cleanup_folio(). We try to
|
||
* drop those buffers here and if that worked, and the
|
||
* folio is no longer mapped into process address space
|
||
* (refcount == 1) it can be freed. Otherwise, leave
|
||
* the folio on the LRU so it is swappable.
|
||
*/
|
||
if (folio_needs_release(folio)) {
|
||
if (!filemap_release_folio(folio, sc->gfp_mask))
|
||
goto activate_locked;
|
||
if (!mapping && folio_ref_count(folio) == 1) {
|
||
folio_unlock(folio);
|
||
if (folio_put_testzero(folio))
|
||
goto free_it;
|
||
else {
|
||
/*
|
||
* rare race with speculative reference.
|
||
* the speculative reference will free
|
||
* this folio shortly, so we may
|
||
* increment nr_reclaimed here (and
|
||
* leave it off the LRU).
|
||
*/
|
||
nr_reclaimed += nr_pages;
|
||
continue;
|
||
}
|
||
}
|
||
}
|
||
|
||
if (folio_test_anon(folio) && !folio_test_swapbacked(folio)) {
|
||
/* follow __remove_mapping for reference */
|
||
if (!folio_ref_freeze(folio, 1))
|
||
goto keep_locked;
|
||
/*
|
||
* The folio has only one reference left, which is
|
||
* from the isolation. After the caller puts the
|
||
* folio back on the lru and drops the reference, the
|
||
* folio will be freed anyway. It doesn't matter
|
||
* which lru it goes on. So we don't bother checking
|
||
* the dirty flag here.
|
||
*/
|
||
count_vm_events(PGLAZYFREED, nr_pages);
|
||
count_memcg_folio_events(folio, PGLAZYFREED, nr_pages);
|
||
} else if (!mapping || !__remove_mapping(mapping, folio, true,
|
||
sc->target_mem_cgroup))
|
||
goto keep_locked;
|
||
|
||
folio_unlock(folio);
|
||
free_it:
|
||
/*
|
||
* Folio may get swapped out as a whole, need to account
|
||
* all pages in it.
|
||
*/
|
||
nr_reclaimed += nr_pages;
|
||
|
||
folio_unqueue_deferred_split(folio);
|
||
if (folio_batch_add(&free_folios, folio) == 0) {
|
||
mem_cgroup_uncharge_folios(&free_folios);
|
||
try_to_unmap_flush();
|
||
free_unref_folios(&free_folios);
|
||
}
|
||
continue;
|
||
|
||
activate_locked_split:
|
||
/*
|
||
* The tail pages that are failed to add into swap cache
|
||
* reach here. Fixup nr_scanned and nr_pages.
|
||
*/
|
||
if (nr_pages > 1) {
|
||
sc->nr_scanned -= (nr_pages - 1);
|
||
nr_pages = 1;
|
||
}
|
||
activate_locked:
|
||
/* Not a candidate for swapping, so reclaim swap space. */
|
||
if (folio_test_swapcache(folio) &&
|
||
(mem_cgroup_swap_full(folio) || folio_test_mlocked(folio)))
|
||
folio_free_swap(folio);
|
||
VM_BUG_ON_FOLIO(folio_test_active(folio), folio);
|
||
if (!folio_test_mlocked(folio)) {
|
||
int type = folio_is_file_lru(folio);
|
||
folio_set_active(folio);
|
||
stat->nr_activate[type] += nr_pages;
|
||
count_memcg_folio_events(folio, PGACTIVATE, nr_pages);
|
||
}
|
||
keep_locked:
|
||
folio_unlock(folio);
|
||
keep:
|
||
list_add(&folio->lru, &ret_folios);
|
||
VM_BUG_ON_FOLIO(folio_test_lru(folio) ||
|
||
folio_test_unevictable(folio), folio);
|
||
}
|
||
/* 'folio_list' is always empty here */
|
||
|
||
/* Migrate folios selected for demotion */
|
||
stat->nr_demoted = demote_folio_list(&demote_folios, pgdat);
|
||
nr_reclaimed += stat->nr_demoted;
|
||
/* Folios that could not be demoted are still in @demote_folios */
|
||
if (!list_empty(&demote_folios)) {
|
||
/* Folios which weren't demoted go back on @folio_list */
|
||
list_splice_init(&demote_folios, folio_list);
|
||
|
||
/*
|
||
* goto retry to reclaim the undemoted folios in folio_list if
|
||
* desired.
|
||
*
|
||
* Reclaiming directly from top tier nodes is not often desired
|
||
* due to it breaking the LRU ordering: in general memory
|
||
* should be reclaimed from lower tier nodes and demoted from
|
||
* top tier nodes.
|
||
*
|
||
* However, disabling reclaim from top tier nodes entirely
|
||
* would cause ooms in edge scenarios where lower tier memory
|
||
* is unreclaimable for whatever reason, eg memory being
|
||
* mlocked or too hot to reclaim. We can disable reclaim
|
||
* from top tier nodes in proactive reclaim though as that is
|
||
* not real memory pressure.
|
||
*/
|
||
if (!sc->proactive) {
|
||
do_demote_pass = false;
|
||
goto retry;
|
||
}
|
||
}
|
||
|
||
pgactivate = stat->nr_activate[0] + stat->nr_activate[1];
|
||
|
||
mem_cgroup_uncharge_folios(&free_folios);
|
||
try_to_unmap_flush();
|
||
free_unref_folios(&free_folios);
|
||
|
||
list_splice(&ret_folios, folio_list);
|
||
count_vm_events(PGACTIVATE, pgactivate);
|
||
|
||
if (plug)
|
||
swap_write_unplug(plug);
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
unsigned int reclaim_clean_pages_from_list(struct zone *zone,
|
||
struct list_head *folio_list)
|
||
{
|
||
struct scan_control sc = {
|
||
.gfp_mask = GFP_KERNEL,
|
||
.may_unmap = 1,
|
||
};
|
||
struct reclaim_stat stat;
|
||
unsigned int nr_reclaimed;
|
||
struct folio *folio, *next;
|
||
LIST_HEAD(clean_folios);
|
||
unsigned int noreclaim_flag;
|
||
|
||
list_for_each_entry_safe(folio, next, folio_list, lru) {
|
||
if (!folio_test_hugetlb(folio) && folio_is_file_lru(folio) &&
|
||
!folio_test_dirty(folio) && !__folio_test_movable(folio) &&
|
||
!folio_test_unevictable(folio)) {
|
||
folio_clear_active(folio);
|
||
list_move(&folio->lru, &clean_folios);
|
||
}
|
||
}
|
||
|
||
/*
|
||
* We should be safe here since we are only dealing with file pages and
|
||
* we are not kswapd and therefore cannot write dirty file pages. But
|
||
* call memalloc_noreclaim_save() anyway, just in case these conditions
|
||
* change in the future.
|
||
*/
|
||
noreclaim_flag = memalloc_noreclaim_save();
|
||
nr_reclaimed = shrink_folio_list(&clean_folios, zone->zone_pgdat, &sc,
|
||
&stat, true);
|
||
memalloc_noreclaim_restore(noreclaim_flag);
|
||
|
||
list_splice(&clean_folios, folio_list);
|
||
mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE,
|
||
-(long)nr_reclaimed);
|
||
/*
|
||
* Since lazyfree pages are isolated from file LRU from the beginning,
|
||
* they will rotate back to anonymous LRU in the end if it failed to
|
||
* discard so isolated count will be mismatched.
|
||
* Compensate the isolated count for both LRU lists.
|
||
*/
|
||
mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_ANON,
|
||
stat.nr_lazyfree_fail);
|
||
mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE,
|
||
-(long)stat.nr_lazyfree_fail);
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
/*
|
||
* Update LRU sizes after isolating pages. The LRU size updates must
|
||
* be complete before mem_cgroup_update_lru_size due to a sanity check.
|
||
*/
|
||
static __always_inline void update_lru_sizes(struct lruvec *lruvec,
|
||
enum lru_list lru, unsigned long *nr_zone_taken)
|
||
{
|
||
int zid;
|
||
|
||
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
|
||
if (!nr_zone_taken[zid])
|
||
continue;
|
||
|
||
update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]);
|
||
}
|
||
|
||
}
|
||
|
||
/*
|
||
* Isolating page from the lruvec to fill in @dst list by nr_to_scan times.
|
||
*
|
||
* lruvec->lru_lock is heavily contended. Some of the functions that
|
||
* shrink the lists perform better by taking out a batch of pages
|
||
* and working on them outside the LRU lock.
|
||
*
|
||
* For pagecache intensive workloads, this function is the hottest
|
||
* spot in the kernel (apart from copy_*_user functions).
|
||
*
|
||
* Lru_lock must be held before calling this function.
|
||
*
|
||
* @nr_to_scan: The number of eligible pages to look through on the list.
|
||
* @lruvec: The LRU vector to pull pages from.
|
||
* @dst: The temp list to put pages on to.
|
||
* @nr_scanned: The number of pages that were scanned.
|
||
* @sc: The scan_control struct for this reclaim session
|
||
* @lru: LRU list id for isolating
|
||
*
|
||
* returns how many pages were moved onto *@dst.
|
||
*/
|
||
static unsigned long isolate_lru_folios(unsigned long nr_to_scan,
|
||
struct lruvec *lruvec, struct list_head *dst,
|
||
unsigned long *nr_scanned, struct scan_control *sc,
|
||
enum lru_list lru)
|
||
{
|
||
struct list_head *src = &lruvec->lists[lru];
|
||
unsigned long nr_taken = 0;
|
||
unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 };
|
||
unsigned long nr_skipped[MAX_NR_ZONES] = { 0, };
|
||
unsigned long skipped = 0;
|
||
unsigned long scan, total_scan, nr_pages;
|
||
LIST_HEAD(folios_skipped);
|
||
|
||
total_scan = 0;
|
||
scan = 0;
|
||
while (scan < nr_to_scan && !list_empty(src)) {
|
||
struct list_head *move_to = src;
|
||
struct folio *folio;
|
||
|
||
folio = lru_to_folio(src);
|
||
prefetchw_prev_lru_folio(folio, src, flags);
|
||
|
||
nr_pages = folio_nr_pages(folio);
|
||
total_scan += nr_pages;
|
||
|
||
if (folio_zonenum(folio) > sc->reclaim_idx) {
|
||
nr_skipped[folio_zonenum(folio)] += nr_pages;
|
||
move_to = &folios_skipped;
|
||
goto move;
|
||
}
|
||
|
||
/*
|
||
* Do not count skipped folios because that makes the function
|
||
* return with no isolated folios if the LRU mostly contains
|
||
* ineligible folios. This causes the VM to not reclaim any
|
||
* folios, triggering a premature OOM.
|
||
* Account all pages in a folio.
|
||
*/
|
||
scan += nr_pages;
|
||
|
||
if (!folio_test_lru(folio))
|
||
goto move;
|
||
if (!sc->may_unmap && folio_mapped(folio))
|
||
goto move;
|
||
|
||
/*
|
||
* Be careful not to clear the lru flag until after we're
|
||
* sure the folio is not being freed elsewhere -- the
|
||
* folio release code relies on it.
|
||
*/
|
||
if (unlikely(!folio_try_get(folio)))
|
||
goto move;
|
||
|
||
if (!folio_test_clear_lru(folio)) {
|
||
/* Another thread is already isolating this folio */
|
||
folio_put(folio);
|
||
goto move;
|
||
}
|
||
|
||
nr_taken += nr_pages;
|
||
nr_zone_taken[folio_zonenum(folio)] += nr_pages;
|
||
move_to = dst;
|
||
move:
|
||
list_move(&folio->lru, move_to);
|
||
}
|
||
|
||
/*
|
||
* Splice any skipped folios to the start of the LRU list. Note that
|
||
* this disrupts the LRU order when reclaiming for lower zones but
|
||
* we cannot splice to the tail. If we did then the SWAP_CLUSTER_MAX
|
||
* scanning would soon rescan the same folios to skip and waste lots
|
||
* of cpu cycles.
|
||
*/
|
||
if (!list_empty(&folios_skipped)) {
|
||
int zid;
|
||
|
||
list_splice(&folios_skipped, src);
|
||
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
|
||
if (!nr_skipped[zid])
|
||
continue;
|
||
|
||
__count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]);
|
||
skipped += nr_skipped[zid];
|
||
}
|
||
}
|
||
*nr_scanned = total_scan;
|
||
trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan,
|
||
total_scan, skipped, nr_taken, lru);
|
||
update_lru_sizes(lruvec, lru, nr_zone_taken);
|
||
return nr_taken;
|
||
}
|
||
|
||
/**
|
||
* folio_isolate_lru() - Try to isolate a folio from its LRU list.
|
||
* @folio: Folio to isolate from its LRU list.
|
||
*
|
||
* Isolate a @folio from an LRU list and adjust the vmstat statistic
|
||
* corresponding to whatever LRU list the folio was on.
|
||
*
|
||
* The folio will have its LRU flag cleared. If it was found on the
|
||
* active list, it will have the Active flag set. If it was found on the
|
||
* unevictable list, it will have the Unevictable flag set. These flags
|
||
* may need to be cleared by the caller before letting the page go.
|
||
*
|
||
* Context:
|
||
*
|
||
* (1) Must be called with an elevated refcount on the folio. This is a
|
||
* fundamental difference from isolate_lru_folios() (which is called
|
||
* without a stable reference).
|
||
* (2) The lru_lock must not be held.
|
||
* (3) Interrupts must be enabled.
|
||
*
|
||
* Return: true if the folio was removed from an LRU list.
|
||
* false if the folio was not on an LRU list.
|
||
*/
|
||
bool folio_isolate_lru(struct folio *folio)
|
||
{
|
||
bool ret = false;
|
||
|
||
VM_BUG_ON_FOLIO(!folio_ref_count(folio), folio);
|
||
|
||
if (folio_test_clear_lru(folio)) {
|
||
struct lruvec *lruvec;
|
||
|
||
folio_get(folio);
|
||
lruvec = folio_lruvec_lock_irq(folio);
|
||
lruvec_del_folio(lruvec, folio);
|
||
unlock_page_lruvec_irq(lruvec);
|
||
ret = true;
|
||
}
|
||
|
||
return ret;
|
||
}
|
||
|
||
/*
|
||
* A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and
|
||
* then get rescheduled. When there are massive number of tasks doing page
|
||
* allocation, such sleeping direct reclaimers may keep piling up on each CPU,
|
||
* the LRU list will go small and be scanned faster than necessary, leading to
|
||
* unnecessary swapping, thrashing and OOM.
|
||
*/
|
||
static bool too_many_isolated(struct pglist_data *pgdat, int file,
|
||
struct scan_control *sc)
|
||
{
|
||
unsigned long inactive, isolated;
|
||
bool too_many;
|
||
|
||
if (current_is_kswapd())
|
||
return false;
|
||
|
||
if (!writeback_throttling_sane(sc))
|
||
return false;
|
||
|
||
if (file) {
|
||
inactive = node_page_state(pgdat, NR_INACTIVE_FILE);
|
||
isolated = node_page_state(pgdat, NR_ISOLATED_FILE);
|
||
} else {
|
||
inactive = node_page_state(pgdat, NR_INACTIVE_ANON);
|
||
isolated = node_page_state(pgdat, NR_ISOLATED_ANON);
|
||
}
|
||
|
||
/*
|
||
* GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they
|
||
* won't get blocked by normal direct-reclaimers, forming a circular
|
||
* deadlock.
|
||
*/
|
||
if (gfp_has_io_fs(sc->gfp_mask))
|
||
inactive >>= 3;
|
||
|
||
too_many = isolated > inactive;
|
||
|
||
/* Wake up tasks throttled due to too_many_isolated. */
|
||
if (!too_many)
|
||
wake_throttle_isolated(pgdat);
|
||
|
||
return too_many;
|
||
}
|
||
|
||
/*
|
||
* move_folios_to_lru() moves folios from private @list to appropriate LRU list.
|
||
*
|
||
* Returns the number of pages moved to the given lruvec.
|
||
*/
|
||
static unsigned int move_folios_to_lru(struct lruvec *lruvec,
|
||
struct list_head *list)
|
||
{
|
||
int nr_pages, nr_moved = 0;
|
||
struct folio_batch free_folios;
|
||
|
||
folio_batch_init(&free_folios);
|
||
while (!list_empty(list)) {
|
||
struct folio *folio = lru_to_folio(list);
|
||
|
||
VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
|
||
list_del(&folio->lru);
|
||
if (unlikely(!folio_evictable(folio))) {
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
folio_putback_lru(folio);
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
continue;
|
||
}
|
||
|
||
/*
|
||
* The folio_set_lru needs to be kept here for list integrity.
|
||
* Otherwise:
|
||
* #0 move_folios_to_lru #1 release_pages
|
||
* if (!folio_put_testzero())
|
||
* if (folio_put_testzero())
|
||
* !lru //skip lru_lock
|
||
* folio_set_lru()
|
||
* list_add(&folio->lru,)
|
||
* list_add(&folio->lru,)
|
||
*/
|
||
folio_set_lru(folio);
|
||
|
||
if (unlikely(folio_put_testzero(folio))) {
|
||
__folio_clear_lru_flags(folio);
|
||
|
||
folio_unqueue_deferred_split(folio);
|
||
if (folio_batch_add(&free_folios, folio) == 0) {
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
mem_cgroup_uncharge_folios(&free_folios);
|
||
free_unref_folios(&free_folios);
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
}
|
||
|
||
continue;
|
||
}
|
||
|
||
/*
|
||
* All pages were isolated from the same lruvec (and isolation
|
||
* inhibits memcg migration).
|
||
*/
|
||
VM_BUG_ON_FOLIO(!folio_matches_lruvec(folio, lruvec), folio);
|
||
lruvec_add_folio(lruvec, folio);
|
||
nr_pages = folio_nr_pages(folio);
|
||
nr_moved += nr_pages;
|
||
if (folio_test_active(folio))
|
||
workingset_age_nonresident(lruvec, nr_pages);
|
||
}
|
||
|
||
if (free_folios.nr) {
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
mem_cgroup_uncharge_folios(&free_folios);
|
||
free_unref_folios(&free_folios);
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
}
|
||
|
||
return nr_moved;
|
||
}
|
||
|
||
/*
|
||
* If a kernel thread (such as nfsd for loop-back mounts) services a backing
|
||
* device by writing to the page cache it sets PF_LOCAL_THROTTLE. In this case
|
||
* we should not throttle. Otherwise it is safe to do so.
|
||
*/
|
||
static int current_may_throttle(void)
|
||
{
|
||
return !(current->flags & PF_LOCAL_THROTTLE);
|
||
}
|
||
|
||
/*
|
||
* shrink_inactive_list() is a helper for shrink_node(). It returns the number
|
||
* of reclaimed pages
|
||
*/
|
||
static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
|
||
struct lruvec *lruvec, struct scan_control *sc,
|
||
enum lru_list lru)
|
||
{
|
||
LIST_HEAD(folio_list);
|
||
unsigned long nr_scanned;
|
||
unsigned int nr_reclaimed = 0;
|
||
unsigned long nr_taken;
|
||
struct reclaim_stat stat;
|
||
bool file = is_file_lru(lru);
|
||
enum vm_event_item item;
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
bool stalled = false;
|
||
|
||
while (unlikely(too_many_isolated(pgdat, file, sc))) {
|
||
if (stalled)
|
||
return 0;
|
||
|
||
/* wait a bit for the reclaimer. */
|
||
stalled = true;
|
||
reclaim_throttle(pgdat, VMSCAN_THROTTLE_ISOLATED);
|
||
|
||
/* We are about to die and free our memory. Return now. */
|
||
if (fatal_signal_pending(current))
|
||
return SWAP_CLUSTER_MAX;
|
||
}
|
||
|
||
lru_add_drain();
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
nr_taken = isolate_lru_folios(nr_to_scan, lruvec, &folio_list,
|
||
&nr_scanned, sc, lru);
|
||
|
||
__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken);
|
||
item = PGSCAN_KSWAPD + reclaimer_offset();
|
||
if (!cgroup_reclaim(sc))
|
||
__count_vm_events(item, nr_scanned);
|
||
__count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned);
|
||
__count_vm_events(PGSCAN_ANON + file, nr_scanned);
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
if (nr_taken == 0)
|
||
return 0;
|
||
|
||
nr_reclaimed = shrink_folio_list(&folio_list, pgdat, sc, &stat, false);
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
move_folios_to_lru(lruvec, &folio_list);
|
||
|
||
__mod_lruvec_state(lruvec, PGDEMOTE_KSWAPD + reclaimer_offset(),
|
||
stat.nr_demoted);
|
||
__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
|
||
item = PGSTEAL_KSWAPD + reclaimer_offset();
|
||
if (!cgroup_reclaim(sc))
|
||
__count_vm_events(item, nr_reclaimed);
|
||
__count_memcg_events(lruvec_memcg(lruvec), item, nr_reclaimed);
|
||
__count_vm_events(PGSTEAL_ANON + file, nr_reclaimed);
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
lru_note_cost(lruvec, file, stat.nr_pageout, nr_scanned - nr_reclaimed);
|
||
|
||
/*
|
||
* If dirty folios are scanned that are not queued for IO, it
|
||
* implies that flushers are not doing their job. This can
|
||
* happen when memory pressure pushes dirty folios to the end of
|
||
* the LRU before the dirty limits are breached and the dirty
|
||
* data has expired. It can also happen when the proportion of
|
||
* dirty folios grows not through writes but through memory
|
||
* pressure reclaiming all the clean cache. And in some cases,
|
||
* the flushers simply cannot keep up with the allocation
|
||
* rate. Nudge the flusher threads in case they are asleep.
|
||
*/
|
||
if (stat.nr_unqueued_dirty == nr_taken) {
|
||
wakeup_flusher_threads(WB_REASON_VMSCAN);
|
||
/*
|
||
* For cgroupv1 dirty throttling is achieved by waking up
|
||
* the kernel flusher here and later waiting on folios
|
||
* which are in writeback to finish (see shrink_folio_list()).
|
||
*
|
||
* Flusher may not be able to issue writeback quickly
|
||
* enough for cgroupv1 writeback throttling to work
|
||
* on a large system.
|
||
*/
|
||
if (!writeback_throttling_sane(sc))
|
||
reclaim_throttle(pgdat, VMSCAN_THROTTLE_WRITEBACK);
|
||
}
|
||
|
||
sc->nr.dirty += stat.nr_dirty;
|
||
sc->nr.congested += stat.nr_congested;
|
||
sc->nr.unqueued_dirty += stat.nr_unqueued_dirty;
|
||
sc->nr.writeback += stat.nr_writeback;
|
||
sc->nr.immediate += stat.nr_immediate;
|
||
sc->nr.taken += nr_taken;
|
||
if (file)
|
||
sc->nr.file_taken += nr_taken;
|
||
|
||
trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id,
|
||
nr_scanned, nr_reclaimed, &stat, sc->priority, file);
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
/*
|
||
* shrink_active_list() moves folios from the active LRU to the inactive LRU.
|
||
*
|
||
* We move them the other way if the folio is referenced by one or more
|
||
* processes.
|
||
*
|
||
* If the folios are mostly unmapped, the processing is fast and it is
|
||
* appropriate to hold lru_lock across the whole operation. But if
|
||
* the folios are mapped, the processing is slow (folio_referenced()), so
|
||
* we should drop lru_lock around each folio. It's impossible to balance
|
||
* this, so instead we remove the folios from the LRU while processing them.
|
||
* It is safe to rely on the active flag against the non-LRU folios in here
|
||
* because nobody will play with that bit on a non-LRU folio.
|
||
*
|
||
* The downside is that we have to touch folio->_refcount against each folio.
|
||
* But we had to alter folio->flags anyway.
|
||
*/
|
||
static void shrink_active_list(unsigned long nr_to_scan,
|
||
struct lruvec *lruvec,
|
||
struct scan_control *sc,
|
||
enum lru_list lru)
|
||
{
|
||
unsigned long nr_taken;
|
||
unsigned long nr_scanned;
|
||
unsigned long vm_flags;
|
||
LIST_HEAD(l_hold); /* The folios which were snipped off */
|
||
LIST_HEAD(l_active);
|
||
LIST_HEAD(l_inactive);
|
||
unsigned nr_deactivate, nr_activate;
|
||
unsigned nr_rotated = 0;
|
||
bool file = is_file_lru(lru);
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
|
||
lru_add_drain();
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
nr_taken = isolate_lru_folios(nr_to_scan, lruvec, &l_hold,
|
||
&nr_scanned, sc, lru);
|
||
|
||
__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken);
|
||
|
||
if (!cgroup_reclaim(sc))
|
||
__count_vm_events(PGREFILL, nr_scanned);
|
||
__count_memcg_events(lruvec_memcg(lruvec), PGREFILL, nr_scanned);
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
while (!list_empty(&l_hold)) {
|
||
struct folio *folio;
|
||
|
||
cond_resched();
|
||
folio = lru_to_folio(&l_hold);
|
||
list_del(&folio->lru);
|
||
|
||
if (unlikely(!folio_evictable(folio))) {
|
||
folio_putback_lru(folio);
|
||
continue;
|
||
}
|
||
|
||
if (unlikely(buffer_heads_over_limit)) {
|
||
if (folio_needs_release(folio) &&
|
||
folio_trylock(folio)) {
|
||
filemap_release_folio(folio, 0);
|
||
folio_unlock(folio);
|
||
}
|
||
}
|
||
|
||
/* Referenced or rmap lock contention: rotate */
|
||
if (folio_referenced(folio, 0, sc->target_mem_cgroup,
|
||
&vm_flags) != 0) {
|
||
/*
|
||
* Identify referenced, file-backed active folios and
|
||
* give them one more trip around the active list. So
|
||
* that executable code get better chances to stay in
|
||
* memory under moderate memory pressure. Anon folios
|
||
* are not likely to be evicted by use-once streaming
|
||
* IO, plus JVM can create lots of anon VM_EXEC folios,
|
||
* so we ignore them here.
|
||
*/
|
||
if ((vm_flags & VM_EXEC) && folio_is_file_lru(folio)) {
|
||
nr_rotated += folio_nr_pages(folio);
|
||
list_add(&folio->lru, &l_active);
|
||
continue;
|
||
}
|
||
}
|
||
|
||
folio_clear_active(folio); /* we are de-activating */
|
||
folio_set_workingset(folio);
|
||
list_add(&folio->lru, &l_inactive);
|
||
}
|
||
|
||
/*
|
||
* Move folios back to the lru list.
|
||
*/
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
nr_activate = move_folios_to_lru(lruvec, &l_active);
|
||
nr_deactivate = move_folios_to_lru(lruvec, &l_inactive);
|
||
|
||
__count_vm_events(PGDEACTIVATE, nr_deactivate);
|
||
__count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate);
|
||
|
||
__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
if (nr_rotated)
|
||
lru_note_cost(lruvec, file, 0, nr_rotated);
|
||
trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate,
|
||
nr_deactivate, nr_rotated, sc->priority, file);
|
||
}
|
||
|
||
static unsigned int reclaim_folio_list(struct list_head *folio_list,
|
||
struct pglist_data *pgdat)
|
||
{
|
||
struct reclaim_stat dummy_stat;
|
||
unsigned int nr_reclaimed;
|
||
struct folio *folio;
|
||
struct scan_control sc = {
|
||
.gfp_mask = GFP_KERNEL,
|
||
.may_writepage = 1,
|
||
.may_unmap = 1,
|
||
.may_swap = 1,
|
||
.no_demotion = 1,
|
||
};
|
||
|
||
nr_reclaimed = shrink_folio_list(folio_list, pgdat, &sc, &dummy_stat, true);
|
||
while (!list_empty(folio_list)) {
|
||
folio = lru_to_folio(folio_list);
|
||
list_del(&folio->lru);
|
||
folio_putback_lru(folio);
|
||
}
|
||
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
unsigned long reclaim_pages(struct list_head *folio_list)
|
||
{
|
||
int nid;
|
||
unsigned int nr_reclaimed = 0;
|
||
LIST_HEAD(node_folio_list);
|
||
unsigned int noreclaim_flag;
|
||
|
||
if (list_empty(folio_list))
|
||
return nr_reclaimed;
|
||
|
||
noreclaim_flag = memalloc_noreclaim_save();
|
||
|
||
nid = folio_nid(lru_to_folio(folio_list));
|
||
do {
|
||
struct folio *folio = lru_to_folio(folio_list);
|
||
|
||
if (nid == folio_nid(folio)) {
|
||
folio_clear_active(folio);
|
||
list_move(&folio->lru, &node_folio_list);
|
||
continue;
|
||
}
|
||
|
||
nr_reclaimed += reclaim_folio_list(&node_folio_list, NODE_DATA(nid));
|
||
nid = folio_nid(lru_to_folio(folio_list));
|
||
} while (!list_empty(folio_list));
|
||
|
||
nr_reclaimed += reclaim_folio_list(&node_folio_list, NODE_DATA(nid));
|
||
|
||
memalloc_noreclaim_restore(noreclaim_flag);
|
||
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
|
||
struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
if (is_active_lru(lru)) {
|
||
if (sc->may_deactivate & (1 << is_file_lru(lru)))
|
||
shrink_active_list(nr_to_scan, lruvec, sc, lru);
|
||
else
|
||
sc->skipped_deactivate = 1;
|
||
return 0;
|
||
}
|
||
|
||
return shrink_inactive_list(nr_to_scan, lruvec, sc, lru);
|
||
}
|
||
|
||
/*
|
||
* The inactive anon list should be small enough that the VM never has
|
||
* to do too much work.
|
||
*
|
||
* The inactive file list should be small enough to leave most memory
|
||
* to the established workingset on the scan-resistant active list,
|
||
* but large enough to avoid thrashing the aggregate readahead window.
|
||
*
|
||
* Both inactive lists should also be large enough that each inactive
|
||
* folio has a chance to be referenced again before it is reclaimed.
|
||
*
|
||
* If that fails and refaulting is observed, the inactive list grows.
|
||
*
|
||
* The inactive_ratio is the target ratio of ACTIVE to INACTIVE folios
|
||
* on this LRU, maintained by the pageout code. An inactive_ratio
|
||
* of 3 means 3:1 or 25% of the folios are kept on the inactive list.
|
||
*
|
||
* total target max
|
||
* memory ratio inactive
|
||
* -------------------------------------
|
||
* 10MB 1 5MB
|
||
* 100MB 1 50MB
|
||
* 1GB 3 250MB
|
||
* 10GB 10 0.9GB
|
||
* 100GB 31 3GB
|
||
* 1TB 101 10GB
|
||
* 10TB 320 32GB
|
||
*/
|
||
static bool inactive_is_low(struct lruvec *lruvec, enum lru_list inactive_lru)
|
||
{
|
||
enum lru_list active_lru = inactive_lru + LRU_ACTIVE;
|
||
unsigned long inactive, active;
|
||
unsigned long inactive_ratio;
|
||
unsigned long gb;
|
||
|
||
inactive = lruvec_page_state(lruvec, NR_LRU_BASE + inactive_lru);
|
||
active = lruvec_page_state(lruvec, NR_LRU_BASE + active_lru);
|
||
|
||
gb = (inactive + active) >> (30 - PAGE_SHIFT);
|
||
if (gb)
|
||
inactive_ratio = int_sqrt(10 * gb);
|
||
else
|
||
inactive_ratio = 1;
|
||
|
||
return inactive * inactive_ratio < active;
|
||
}
|
||
|
||
enum scan_balance {
|
||
SCAN_EQUAL,
|
||
SCAN_FRACT,
|
||
SCAN_ANON,
|
||
SCAN_FILE,
|
||
};
|
||
|
||
static void prepare_scan_control(pg_data_t *pgdat, struct scan_control *sc)
|
||
{
|
||
unsigned long file;
|
||
struct lruvec *target_lruvec;
|
||
|
||
if (lru_gen_enabled())
|
||
return;
|
||
|
||
target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat);
|
||
|
||
/*
|
||
* Flush the memory cgroup stats in rate-limited way as we don't need
|
||
* most accurate stats here. We may switch to regular stats flushing
|
||
* in the future once it is cheap enough.
|
||
*/
|
||
mem_cgroup_flush_stats_ratelimited(sc->target_mem_cgroup);
|
||
|
||
/*
|
||
* Determine the scan balance between anon and file LRUs.
|
||
*/
|
||
spin_lock_irq(&target_lruvec->lru_lock);
|
||
sc->anon_cost = target_lruvec->anon_cost;
|
||
sc->file_cost = target_lruvec->file_cost;
|
||
spin_unlock_irq(&target_lruvec->lru_lock);
|
||
|
||
/*
|
||
* Target desirable inactive:active list ratios for the anon
|
||
* and file LRU lists.
|
||
*/
|
||
if (!sc->force_deactivate) {
|
||
unsigned long refaults;
|
||
|
||
/*
|
||
* When refaults are being observed, it means a new
|
||
* workingset is being established. Deactivate to get
|
||
* rid of any stale active pages quickly.
|
||
*/
|
||
refaults = lruvec_page_state(target_lruvec,
|
||
WORKINGSET_ACTIVATE_ANON);
|
||
if (refaults != target_lruvec->refaults[WORKINGSET_ANON] ||
|
||
inactive_is_low(target_lruvec, LRU_INACTIVE_ANON))
|
||
sc->may_deactivate |= DEACTIVATE_ANON;
|
||
else
|
||
sc->may_deactivate &= ~DEACTIVATE_ANON;
|
||
|
||
refaults = lruvec_page_state(target_lruvec,
|
||
WORKINGSET_ACTIVATE_FILE);
|
||
if (refaults != target_lruvec->refaults[WORKINGSET_FILE] ||
|
||
inactive_is_low(target_lruvec, LRU_INACTIVE_FILE))
|
||
sc->may_deactivate |= DEACTIVATE_FILE;
|
||
else
|
||
sc->may_deactivate &= ~DEACTIVATE_FILE;
|
||
} else
|
||
sc->may_deactivate = DEACTIVATE_ANON | DEACTIVATE_FILE;
|
||
|
||
/*
|
||
* If we have plenty of inactive file pages that aren't
|
||
* thrashing, try to reclaim those first before touching
|
||
* anonymous pages.
|
||
*/
|
||
file = lruvec_page_state(target_lruvec, NR_INACTIVE_FILE);
|
||
if (file >> sc->priority && !(sc->may_deactivate & DEACTIVATE_FILE) &&
|
||
!sc->no_cache_trim_mode)
|
||
sc->cache_trim_mode = 1;
|
||
else
|
||
sc->cache_trim_mode = 0;
|
||
|
||
/*
|
||
* Prevent the reclaimer from falling into the cache trap: as
|
||
* cache pages start out inactive, every cache fault will tip
|
||
* the scan balance towards the file LRU. And as the file LRU
|
||
* shrinks, so does the window for rotation from references.
|
||
* This means we have a runaway feedback loop where a tiny
|
||
* thrashing file LRU becomes infinitely more attractive than
|
||
* anon pages. Try to detect this based on file LRU size.
|
||
*/
|
||
if (!cgroup_reclaim(sc)) {
|
||
unsigned long total_high_wmark = 0;
|
||
unsigned long free, anon;
|
||
int z;
|
||
|
||
free = sum_zone_node_page_state(pgdat->node_id, NR_FREE_PAGES);
|
||
file = node_page_state(pgdat, NR_ACTIVE_FILE) +
|
||
node_page_state(pgdat, NR_INACTIVE_FILE);
|
||
|
||
for (z = 0; z < MAX_NR_ZONES; z++) {
|
||
struct zone *zone = &pgdat->node_zones[z];
|
||
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
total_high_wmark += high_wmark_pages(zone);
|
||
}
|
||
|
||
/*
|
||
* Consider anon: if that's low too, this isn't a
|
||
* runaway file reclaim problem, but rather just
|
||
* extreme pressure. Reclaim as per usual then.
|
||
*/
|
||
anon = node_page_state(pgdat, NR_INACTIVE_ANON);
|
||
|
||
sc->file_is_tiny =
|
||
file + free <= total_high_wmark &&
|
||
!(sc->may_deactivate & DEACTIVATE_ANON) &&
|
||
anon >> sc->priority;
|
||
}
|
||
}
|
||
|
||
/*
|
||
* Determine how aggressively the anon and file LRU lists should be
|
||
* scanned.
|
||
*
|
||
* nr[0] = anon inactive folios to scan; nr[1] = anon active folios to scan
|
||
* nr[2] = file inactive folios to scan; nr[3] = file active folios to scan
|
||
*/
|
||
static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
|
||
unsigned long *nr)
|
||
{
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
unsigned long anon_cost, file_cost, total_cost;
|
||
int swappiness = sc_swappiness(sc, memcg);
|
||
u64 fraction[ANON_AND_FILE];
|
||
u64 denominator = 0; /* gcc */
|
||
enum scan_balance scan_balance;
|
||
unsigned long ap, fp;
|
||
enum lru_list lru;
|
||
|
||
/* If we have no swap space, do not bother scanning anon folios. */
|
||
if (!sc->may_swap || !can_reclaim_anon_pages(memcg, pgdat->node_id, sc)) {
|
||
scan_balance = SCAN_FILE;
|
||
goto out;
|
||
}
|
||
|
||
/*
|
||
* Global reclaim will swap to prevent OOM even with no
|
||
* swappiness, but memcg users want to use this knob to
|
||
* disable swapping for individual groups completely when
|
||
* using the memory controller's swap limit feature would be
|
||
* too expensive.
|
||
*/
|
||
if (cgroup_reclaim(sc) && !swappiness) {
|
||
scan_balance = SCAN_FILE;
|
||
goto out;
|
||
}
|
||
|
||
/*
|
||
* Do not apply any pressure balancing cleverness when the
|
||
* system is close to OOM, scan both anon and file equally
|
||
* (unless the swappiness setting disagrees with swapping).
|
||
*/
|
||
if (!sc->priority && swappiness) {
|
||
scan_balance = SCAN_EQUAL;
|
||
goto out;
|
||
}
|
||
|
||
/*
|
||
* If the system is almost out of file pages, force-scan anon.
|
||
*/
|
||
if (sc->file_is_tiny) {
|
||
scan_balance = SCAN_ANON;
|
||
goto out;
|
||
}
|
||
|
||
/*
|
||
* If there is enough inactive page cache, we do not reclaim
|
||
* anything from the anonymous working right now.
|
||
*/
|
||
if (sc->cache_trim_mode) {
|
||
scan_balance = SCAN_FILE;
|
||
goto out;
|
||
}
|
||
|
||
scan_balance = SCAN_FRACT;
|
||
/*
|
||
* Calculate the pressure balance between anon and file pages.
|
||
*
|
||
* The amount of pressure we put on each LRU is inversely
|
||
* proportional to the cost of reclaiming each list, as
|
||
* determined by the share of pages that are refaulting, times
|
||
* the relative IO cost of bringing back a swapped out
|
||
* anonymous page vs reloading a filesystem page (swappiness).
|
||
*
|
||
* Although we limit that influence to ensure no list gets
|
||
* left behind completely: at least a third of the pressure is
|
||
* applied, before swappiness.
|
||
*
|
||
* With swappiness at 100, anon and file have equal IO cost.
|
||
*/
|
||
total_cost = sc->anon_cost + sc->file_cost;
|
||
anon_cost = total_cost + sc->anon_cost;
|
||
file_cost = total_cost + sc->file_cost;
|
||
total_cost = anon_cost + file_cost;
|
||
|
||
ap = swappiness * (total_cost + 1);
|
||
ap /= anon_cost + 1;
|
||
|
||
fp = (MAX_SWAPPINESS - swappiness) * (total_cost + 1);
|
||
fp /= file_cost + 1;
|
||
|
||
fraction[0] = ap;
|
||
fraction[1] = fp;
|
||
denominator = ap + fp;
|
||
out:
|
||
for_each_evictable_lru(lru) {
|
||
bool file = is_file_lru(lru);
|
||
unsigned long lruvec_size;
|
||
unsigned long low, min;
|
||
unsigned long scan;
|
||
|
||
lruvec_size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
|
||
mem_cgroup_protection(sc->target_mem_cgroup, memcg,
|
||
&min, &low);
|
||
|
||
if (min || low) {
|
||
/*
|
||
* Scale a cgroup's reclaim pressure by proportioning
|
||
* its current usage to its memory.low or memory.min
|
||
* setting.
|
||
*
|
||
* This is important, as otherwise scanning aggression
|
||
* becomes extremely binary -- from nothing as we
|
||
* approach the memory protection threshold, to totally
|
||
* nominal as we exceed it. This results in requiring
|
||
* setting extremely liberal protection thresholds. It
|
||
* also means we simply get no protection at all if we
|
||
* set it too low, which is not ideal.
|
||
*
|
||
* If there is any protection in place, we reduce scan
|
||
* pressure by how much of the total memory used is
|
||
* within protection thresholds.
|
||
*
|
||
* There is one special case: in the first reclaim pass,
|
||
* we skip over all groups that are within their low
|
||
* protection. If that fails to reclaim enough pages to
|
||
* satisfy the reclaim goal, we come back and override
|
||
* the best-effort low protection. However, we still
|
||
* ideally want to honor how well-behaved groups are in
|
||
* that case instead of simply punishing them all
|
||
* equally. As such, we reclaim them based on how much
|
||
* memory they are using, reducing the scan pressure
|
||
* again by how much of the total memory used is under
|
||
* hard protection.
|
||
*/
|
||
unsigned long cgroup_size = mem_cgroup_size(memcg);
|
||
unsigned long protection;
|
||
|
||
/* memory.low scaling, make sure we retry before OOM */
|
||
if (!sc->memcg_low_reclaim && low > min) {
|
||
protection = low;
|
||
sc->memcg_low_skipped = 1;
|
||
} else {
|
||
protection = min;
|
||
}
|
||
|
||
/* Avoid TOCTOU with earlier protection check */
|
||
cgroup_size = max(cgroup_size, protection);
|
||
|
||
scan = lruvec_size - lruvec_size * protection /
|
||
(cgroup_size + 1);
|
||
|
||
/*
|
||
* Minimally target SWAP_CLUSTER_MAX pages to keep
|
||
* reclaim moving forwards, avoiding decrementing
|
||
* sc->priority further than desirable.
|
||
*/
|
||
scan = max(scan, SWAP_CLUSTER_MAX);
|
||
} else {
|
||
scan = lruvec_size;
|
||
}
|
||
|
||
scan >>= sc->priority;
|
||
|
||
/*
|
||
* If the cgroup's already been deleted, make sure to
|
||
* scrape out the remaining cache.
|
||
*/
|
||
if (!scan && !mem_cgroup_online(memcg))
|
||
scan = min(lruvec_size, SWAP_CLUSTER_MAX);
|
||
|
||
switch (scan_balance) {
|
||
case SCAN_EQUAL:
|
||
/* Scan lists relative to size */
|
||
break;
|
||
case SCAN_FRACT:
|
||
/*
|
||
* Scan types proportional to swappiness and
|
||
* their relative recent reclaim efficiency.
|
||
* Make sure we don't miss the last page on
|
||
* the offlined memory cgroups because of a
|
||
* round-off error.
|
||
*/
|
||
scan = mem_cgroup_online(memcg) ?
|
||
div64_u64(scan * fraction[file], denominator) :
|
||
DIV64_U64_ROUND_UP(scan * fraction[file],
|
||
denominator);
|
||
break;
|
||
case SCAN_FILE:
|
||
case SCAN_ANON:
|
||
/* Scan one type exclusively */
|
||
if ((scan_balance == SCAN_FILE) != file)
|
||
scan = 0;
|
||
break;
|
||
default:
|
||
/* Look ma, no brain */
|
||
BUG();
|
||
}
|
||
|
||
nr[lru] = scan;
|
||
}
|
||
}
|
||
|
||
/*
|
||
* Anonymous LRU management is a waste if there is
|
||
* ultimately no way to reclaim the memory.
|
||
*/
|
||
static bool can_age_anon_pages(struct pglist_data *pgdat,
|
||
struct scan_control *sc)
|
||
{
|
||
/* Aging the anon LRU is valuable if swap is present: */
|
||
if (total_swap_pages > 0)
|
||
return true;
|
||
|
||
/* Also valuable if anon pages can be demoted: */
|
||
return can_demote(pgdat->node_id, sc);
|
||
}
|
||
|
||
#ifdef CONFIG_LRU_GEN
|
||
|
||
#ifdef CONFIG_LRU_GEN_ENABLED
|
||
DEFINE_STATIC_KEY_ARRAY_TRUE(lru_gen_caps, NR_LRU_GEN_CAPS);
|
||
#define get_cap(cap) static_branch_likely(&lru_gen_caps[cap])
|
||
#else
|
||
DEFINE_STATIC_KEY_ARRAY_FALSE(lru_gen_caps, NR_LRU_GEN_CAPS);
|
||
#define get_cap(cap) static_branch_unlikely(&lru_gen_caps[cap])
|
||
#endif
|
||
|
||
static bool should_walk_mmu(void)
|
||
{
|
||
return arch_has_hw_pte_young() && get_cap(LRU_GEN_MM_WALK);
|
||
}
|
||
|
||
static bool should_clear_pmd_young(void)
|
||
{
|
||
return arch_has_hw_nonleaf_pmd_young() && get_cap(LRU_GEN_NONLEAF_YOUNG);
|
||
}
|
||
|
||
/******************************************************************************
|
||
* shorthand helpers
|
||
******************************************************************************/
|
||
|
||
#define LRU_REFS_FLAGS (BIT(PG_referenced) | BIT(PG_workingset))
|
||
|
||
#define DEFINE_MAX_SEQ(lruvec) \
|
||
unsigned long max_seq = READ_ONCE((lruvec)->lrugen.max_seq)
|
||
|
||
#define DEFINE_MIN_SEQ(lruvec) \
|
||
unsigned long min_seq[ANON_AND_FILE] = { \
|
||
READ_ONCE((lruvec)->lrugen.min_seq[LRU_GEN_ANON]), \
|
||
READ_ONCE((lruvec)->lrugen.min_seq[LRU_GEN_FILE]), \
|
||
}
|
||
|
||
#define for_each_gen_type_zone(gen, type, zone) \
|
||
for ((gen) = 0; (gen) < MAX_NR_GENS; (gen)++) \
|
||
for ((type) = 0; (type) < ANON_AND_FILE; (type)++) \
|
||
for ((zone) = 0; (zone) < MAX_NR_ZONES; (zone)++)
|
||
|
||
#define get_memcg_gen(seq) ((seq) % MEMCG_NR_GENS)
|
||
#define get_memcg_bin(bin) ((bin) % MEMCG_NR_BINS)
|
||
|
||
static struct lruvec *get_lruvec(struct mem_cgroup *memcg, int nid)
|
||
{
|
||
struct pglist_data *pgdat = NODE_DATA(nid);
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
if (memcg) {
|
||
struct lruvec *lruvec = &memcg->nodeinfo[nid]->lruvec;
|
||
|
||
/* see the comment in mem_cgroup_lruvec() */
|
||
if (!lruvec->pgdat)
|
||
lruvec->pgdat = pgdat;
|
||
|
||
return lruvec;
|
||
}
|
||
#endif
|
||
VM_WARN_ON_ONCE(!mem_cgroup_disabled());
|
||
|
||
return &pgdat->__lruvec;
|
||
}
|
||
|
||
static int get_swappiness(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
|
||
if (!sc->may_swap)
|
||
return 0;
|
||
|
||
if (!can_demote(pgdat->node_id, sc) &&
|
||
mem_cgroup_get_nr_swap_pages(memcg) < MIN_LRU_BATCH)
|
||
return 0;
|
||
|
||
return sc_swappiness(sc, memcg);
|
||
}
|
||
|
||
static int get_nr_gens(struct lruvec *lruvec, int type)
|
||
{
|
||
return lruvec->lrugen.max_seq - lruvec->lrugen.min_seq[type] + 1;
|
||
}
|
||
|
||
static bool __maybe_unused seq_is_valid(struct lruvec *lruvec)
|
||
{
|
||
/* see the comment on lru_gen_folio */
|
||
return get_nr_gens(lruvec, LRU_GEN_FILE) >= MIN_NR_GENS &&
|
||
get_nr_gens(lruvec, LRU_GEN_FILE) <= get_nr_gens(lruvec, LRU_GEN_ANON) &&
|
||
get_nr_gens(lruvec, LRU_GEN_ANON) <= MAX_NR_GENS;
|
||
}
|
||
|
||
/******************************************************************************
|
||
* Bloom filters
|
||
******************************************************************************/
|
||
|
||
/*
|
||
* Bloom filters with m=1<<15, k=2 and the false positive rates of ~1/5 when
|
||
* n=10,000 and ~1/2 when n=20,000, where, conventionally, m is the number of
|
||
* bits in a bitmap, k is the number of hash functions and n is the number of
|
||
* inserted items.
|
||
*
|
||
* Page table walkers use one of the two filters to reduce their search space.
|
||
* To get rid of non-leaf entries that no longer have enough leaf entries, the
|
||
* aging uses the double-buffering technique to flip to the other filter each
|
||
* time it produces a new generation. For non-leaf entries that have enough
|
||
* leaf entries, the aging carries them over to the next generation in
|
||
* walk_pmd_range(); the eviction also report them when walking the rmap
|
||
* in lru_gen_look_around().
|
||
*
|
||
* For future optimizations:
|
||
* 1. It's not necessary to keep both filters all the time. The spare one can be
|
||
* freed after the RCU grace period and reallocated if needed again.
|
||
* 2. And when reallocating, it's worth scaling its size according to the number
|
||
* of inserted entries in the other filter, to reduce the memory overhead on
|
||
* small systems and false positives on large systems.
|
||
* 3. Jenkins' hash function is an alternative to Knuth's.
|
||
*/
|
||
#define BLOOM_FILTER_SHIFT 15
|
||
|
||
static inline int filter_gen_from_seq(unsigned long seq)
|
||
{
|
||
return seq % NR_BLOOM_FILTERS;
|
||
}
|
||
|
||
static void get_item_key(void *item, int *key)
|
||
{
|
||
u32 hash = hash_ptr(item, BLOOM_FILTER_SHIFT * 2);
|
||
|
||
BUILD_BUG_ON(BLOOM_FILTER_SHIFT * 2 > BITS_PER_TYPE(u32));
|
||
|
||
key[0] = hash & (BIT(BLOOM_FILTER_SHIFT) - 1);
|
||
key[1] = hash >> BLOOM_FILTER_SHIFT;
|
||
}
|
||
|
||
static bool test_bloom_filter(struct lru_gen_mm_state *mm_state, unsigned long seq,
|
||
void *item)
|
||
{
|
||
int key[2];
|
||
unsigned long *filter;
|
||
int gen = filter_gen_from_seq(seq);
|
||
|
||
filter = READ_ONCE(mm_state->filters[gen]);
|
||
if (!filter)
|
||
return true;
|
||
|
||
get_item_key(item, key);
|
||
|
||
return test_bit(key[0], filter) && test_bit(key[1], filter);
|
||
}
|
||
|
||
static void update_bloom_filter(struct lru_gen_mm_state *mm_state, unsigned long seq,
|
||
void *item)
|
||
{
|
||
int key[2];
|
||
unsigned long *filter;
|
||
int gen = filter_gen_from_seq(seq);
|
||
|
||
filter = READ_ONCE(mm_state->filters[gen]);
|
||
if (!filter)
|
||
return;
|
||
|
||
get_item_key(item, key);
|
||
|
||
if (!test_bit(key[0], filter))
|
||
set_bit(key[0], filter);
|
||
if (!test_bit(key[1], filter))
|
||
set_bit(key[1], filter);
|
||
}
|
||
|
||
static void reset_bloom_filter(struct lru_gen_mm_state *mm_state, unsigned long seq)
|
||
{
|
||
unsigned long *filter;
|
||
int gen = filter_gen_from_seq(seq);
|
||
|
||
filter = mm_state->filters[gen];
|
||
if (filter) {
|
||
bitmap_clear(filter, 0, BIT(BLOOM_FILTER_SHIFT));
|
||
return;
|
||
}
|
||
|
||
filter = bitmap_zalloc(BIT(BLOOM_FILTER_SHIFT),
|
||
__GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN);
|
||
WRITE_ONCE(mm_state->filters[gen], filter);
|
||
}
|
||
|
||
/******************************************************************************
|
||
* mm_struct list
|
||
******************************************************************************/
|
||
|
||
#ifdef CONFIG_LRU_GEN_WALKS_MMU
|
||
|
||
static struct lru_gen_mm_list *get_mm_list(struct mem_cgroup *memcg)
|
||
{
|
||
static struct lru_gen_mm_list mm_list = {
|
||
.fifo = LIST_HEAD_INIT(mm_list.fifo),
|
||
.lock = __SPIN_LOCK_UNLOCKED(mm_list.lock),
|
||
};
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
if (memcg)
|
||
return &memcg->mm_list;
|
||
#endif
|
||
VM_WARN_ON_ONCE(!mem_cgroup_disabled());
|
||
|
||
return &mm_list;
|
||
}
|
||
|
||
static struct lru_gen_mm_state *get_mm_state(struct lruvec *lruvec)
|
||
{
|
||
return &lruvec->mm_state;
|
||
}
|
||
|
||
static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)
|
||
{
|
||
int key;
|
||
struct mm_struct *mm;
|
||
struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(walk->lruvec);
|
||
|
||
mm = list_entry(mm_state->head, struct mm_struct, lru_gen.list);
|
||
key = pgdat->node_id % BITS_PER_TYPE(mm->lru_gen.bitmap);
|
||
|
||
if (!walk->force_scan && !test_bit(key, &mm->lru_gen.bitmap))
|
||
return NULL;
|
||
|
||
clear_bit(key, &mm->lru_gen.bitmap);
|
||
|
||
return mmget_not_zero(mm) ? mm : NULL;
|
||
}
|
||
|
||
void lru_gen_add_mm(struct mm_struct *mm)
|
||
{
|
||
int nid;
|
||
struct mem_cgroup *memcg = get_mem_cgroup_from_mm(mm);
|
||
struct lru_gen_mm_list *mm_list = get_mm_list(memcg);
|
||
|
||
VM_WARN_ON_ONCE(!list_empty(&mm->lru_gen.list));
|
||
#ifdef CONFIG_MEMCG
|
||
VM_WARN_ON_ONCE(mm->lru_gen.memcg);
|
||
mm->lru_gen.memcg = memcg;
|
||
#endif
|
||
spin_lock(&mm_list->lock);
|
||
|
||
for_each_node_state(nid, N_MEMORY) {
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
/* the first addition since the last iteration */
|
||
if (mm_state->tail == &mm_list->fifo)
|
||
mm_state->tail = &mm->lru_gen.list;
|
||
}
|
||
|
||
list_add_tail(&mm->lru_gen.list, &mm_list->fifo);
|
||
|
||
spin_unlock(&mm_list->lock);
|
||
}
|
||
|
||
void lru_gen_del_mm(struct mm_struct *mm)
|
||
{
|
||
int nid;
|
||
struct lru_gen_mm_list *mm_list;
|
||
struct mem_cgroup *memcg = NULL;
|
||
|
||
if (list_empty(&mm->lru_gen.list))
|
||
return;
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
memcg = mm->lru_gen.memcg;
|
||
#endif
|
||
mm_list = get_mm_list(memcg);
|
||
|
||
spin_lock(&mm_list->lock);
|
||
|
||
for_each_node(nid) {
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
/* where the current iteration continues after */
|
||
if (mm_state->head == &mm->lru_gen.list)
|
||
mm_state->head = mm_state->head->prev;
|
||
|
||
/* where the last iteration ended before */
|
||
if (mm_state->tail == &mm->lru_gen.list)
|
||
mm_state->tail = mm_state->tail->next;
|
||
}
|
||
|
||
list_del_init(&mm->lru_gen.list);
|
||
|
||
spin_unlock(&mm_list->lock);
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
mem_cgroup_put(mm->lru_gen.memcg);
|
||
mm->lru_gen.memcg = NULL;
|
||
#endif
|
||
}
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
void lru_gen_migrate_mm(struct mm_struct *mm)
|
||
{
|
||
struct mem_cgroup *memcg;
|
||
struct task_struct *task = rcu_dereference_protected(mm->owner, true);
|
||
|
||
VM_WARN_ON_ONCE(task->mm != mm);
|
||
lockdep_assert_held(&task->alloc_lock);
|
||
|
||
/* for mm_update_next_owner() */
|
||
if (mem_cgroup_disabled())
|
||
return;
|
||
|
||
/* migration can happen before addition */
|
||
if (!mm->lru_gen.memcg)
|
||
return;
|
||
|
||
rcu_read_lock();
|
||
memcg = mem_cgroup_from_task(task);
|
||
rcu_read_unlock();
|
||
if (memcg == mm->lru_gen.memcg)
|
||
return;
|
||
|
||
VM_WARN_ON_ONCE(list_empty(&mm->lru_gen.list));
|
||
|
||
lru_gen_del_mm(mm);
|
||
lru_gen_add_mm(mm);
|
||
}
|
||
#endif
|
||
|
||
#else /* !CONFIG_LRU_GEN_WALKS_MMU */
|
||
|
||
static struct lru_gen_mm_list *get_mm_list(struct mem_cgroup *memcg)
|
||
{
|
||
return NULL;
|
||
}
|
||
|
||
static struct lru_gen_mm_state *get_mm_state(struct lruvec *lruvec)
|
||
{
|
||
return NULL;
|
||
}
|
||
|
||
static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)
|
||
{
|
||
return NULL;
|
||
}
|
||
|
||
#endif
|
||
|
||
static void reset_mm_stats(struct lru_gen_mm_walk *walk, bool last)
|
||
{
|
||
int i;
|
||
int hist;
|
||
struct lruvec *lruvec = walk->lruvec;
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
lockdep_assert_held(&get_mm_list(lruvec_memcg(lruvec))->lock);
|
||
|
||
hist = lru_hist_from_seq(walk->seq);
|
||
|
||
for (i = 0; i < NR_MM_STATS; i++) {
|
||
WRITE_ONCE(mm_state->stats[hist][i],
|
||
mm_state->stats[hist][i] + walk->mm_stats[i]);
|
||
walk->mm_stats[i] = 0;
|
||
}
|
||
|
||
if (NR_HIST_GENS > 1 && last) {
|
||
hist = lru_hist_from_seq(walk->seq + 1);
|
||
|
||
for (i = 0; i < NR_MM_STATS; i++)
|
||
WRITE_ONCE(mm_state->stats[hist][i], 0);
|
||
}
|
||
}
|
||
|
||
static bool iterate_mm_list(struct lru_gen_mm_walk *walk, struct mm_struct **iter)
|
||
{
|
||
bool first = false;
|
||
bool last = false;
|
||
struct mm_struct *mm = NULL;
|
||
struct lruvec *lruvec = walk->lruvec;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
struct lru_gen_mm_list *mm_list = get_mm_list(memcg);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
/*
|
||
* mm_state->seq is incremented after each iteration of mm_list. There
|
||
* are three interesting cases for this page table walker:
|
||
* 1. It tries to start a new iteration with a stale max_seq: there is
|
||
* nothing left to do.
|
||
* 2. It started the next iteration: it needs to reset the Bloom filter
|
||
* so that a fresh set of PTE tables can be recorded.
|
||
* 3. It ended the current iteration: it needs to reset the mm stats
|
||
* counters and tell its caller to increment max_seq.
|
||
*/
|
||
spin_lock(&mm_list->lock);
|
||
|
||
VM_WARN_ON_ONCE(mm_state->seq + 1 < walk->seq);
|
||
|
||
if (walk->seq <= mm_state->seq)
|
||
goto done;
|
||
|
||
if (!mm_state->head)
|
||
mm_state->head = &mm_list->fifo;
|
||
|
||
if (mm_state->head == &mm_list->fifo)
|
||
first = true;
|
||
|
||
do {
|
||
mm_state->head = mm_state->head->next;
|
||
if (mm_state->head == &mm_list->fifo) {
|
||
WRITE_ONCE(mm_state->seq, mm_state->seq + 1);
|
||
last = true;
|
||
break;
|
||
}
|
||
|
||
/* force scan for those added after the last iteration */
|
||
if (!mm_state->tail || mm_state->tail == mm_state->head) {
|
||
mm_state->tail = mm_state->head->next;
|
||
walk->force_scan = true;
|
||
}
|
||
} while (!(mm = get_next_mm(walk)));
|
||
done:
|
||
if (*iter || last)
|
||
reset_mm_stats(walk, last);
|
||
|
||
spin_unlock(&mm_list->lock);
|
||
|
||
if (mm && first)
|
||
reset_bloom_filter(mm_state, walk->seq + 1);
|
||
|
||
if (*iter)
|
||
mmput_async(*iter);
|
||
|
||
*iter = mm;
|
||
|
||
return last;
|
||
}
|
||
|
||
static bool iterate_mm_list_nowalk(struct lruvec *lruvec, unsigned long seq)
|
||
{
|
||
bool success = false;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
struct lru_gen_mm_list *mm_list = get_mm_list(memcg);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
spin_lock(&mm_list->lock);
|
||
|
||
VM_WARN_ON_ONCE(mm_state->seq + 1 < seq);
|
||
|
||
if (seq > mm_state->seq) {
|
||
mm_state->head = NULL;
|
||
mm_state->tail = NULL;
|
||
WRITE_ONCE(mm_state->seq, mm_state->seq + 1);
|
||
success = true;
|
||
}
|
||
|
||
spin_unlock(&mm_list->lock);
|
||
|
||
return success;
|
||
}
|
||
|
||
/******************************************************************************
|
||
* PID controller
|
||
******************************************************************************/
|
||
|
||
/*
|
||
* A feedback loop based on Proportional-Integral-Derivative (PID) controller.
|
||
*
|
||
* The P term is refaulted/(evicted+protected) from a tier in the generation
|
||
* currently being evicted; the I term is the exponential moving average of the
|
||
* P term over the generations previously evicted, using the smoothing factor
|
||
* 1/2; the D term isn't supported.
|
||
*
|
||
* The setpoint (SP) is always the first tier of one type; the process variable
|
||
* (PV) is either any tier of the other type or any other tier of the same
|
||
* type.
|
||
*
|
||
* The error is the difference between the SP and the PV; the correction is to
|
||
* turn off protection when SP>PV or turn on protection when SP<PV.
|
||
*
|
||
* For future optimizations:
|
||
* 1. The D term may discount the other two terms over time so that long-lived
|
||
* generations can resist stale information.
|
||
*/
|
||
struct ctrl_pos {
|
||
unsigned long refaulted;
|
||
unsigned long total;
|
||
int gain;
|
||
};
|
||
|
||
static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier, int gain,
|
||
struct ctrl_pos *pos)
|
||
{
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
int hist = lru_hist_from_seq(lrugen->min_seq[type]);
|
||
|
||
pos->refaulted = lrugen->avg_refaulted[type][tier] +
|
||
atomic_long_read(&lrugen->refaulted[hist][type][tier]);
|
||
pos->total = lrugen->avg_total[type][tier] +
|
||
atomic_long_read(&lrugen->evicted[hist][type][tier]);
|
||
if (tier)
|
||
pos->total += lrugen->protected[hist][type][tier - 1];
|
||
pos->gain = gain;
|
||
}
|
||
|
||
static void reset_ctrl_pos(struct lruvec *lruvec, int type, bool carryover)
|
||
{
|
||
int hist, tier;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
bool clear = carryover ? NR_HIST_GENS == 1 : NR_HIST_GENS > 1;
|
||
unsigned long seq = carryover ? lrugen->min_seq[type] : lrugen->max_seq + 1;
|
||
|
||
lockdep_assert_held(&lruvec->lru_lock);
|
||
|
||
if (!carryover && !clear)
|
||
return;
|
||
|
||
hist = lru_hist_from_seq(seq);
|
||
|
||
for (tier = 0; tier < MAX_NR_TIERS; tier++) {
|
||
if (carryover) {
|
||
unsigned long sum;
|
||
|
||
sum = lrugen->avg_refaulted[type][tier] +
|
||
atomic_long_read(&lrugen->refaulted[hist][type][tier]);
|
||
WRITE_ONCE(lrugen->avg_refaulted[type][tier], sum / 2);
|
||
|
||
sum = lrugen->avg_total[type][tier] +
|
||
atomic_long_read(&lrugen->evicted[hist][type][tier]);
|
||
if (tier)
|
||
sum += lrugen->protected[hist][type][tier - 1];
|
||
WRITE_ONCE(lrugen->avg_total[type][tier], sum / 2);
|
||
}
|
||
|
||
if (clear) {
|
||
atomic_long_set(&lrugen->refaulted[hist][type][tier], 0);
|
||
atomic_long_set(&lrugen->evicted[hist][type][tier], 0);
|
||
if (tier)
|
||
WRITE_ONCE(lrugen->protected[hist][type][tier - 1], 0);
|
||
}
|
||
}
|
||
}
|
||
|
||
static bool positive_ctrl_err(struct ctrl_pos *sp, struct ctrl_pos *pv)
|
||
{
|
||
/*
|
||
* Return true if the PV has a limited number of refaults or a lower
|
||
* refaulted/total than the SP.
|
||
*/
|
||
return pv->refaulted < MIN_LRU_BATCH ||
|
||
pv->refaulted * (sp->total + MIN_LRU_BATCH) * sp->gain <=
|
||
(sp->refaulted + 1) * pv->total * pv->gain;
|
||
}
|
||
|
||
/******************************************************************************
|
||
* the aging
|
||
******************************************************************************/
|
||
|
||
/* promote pages accessed through page tables */
|
||
static int folio_update_gen(struct folio *folio, int gen)
|
||
{
|
||
unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
|
||
|
||
VM_WARN_ON_ONCE(gen >= MAX_NR_GENS);
|
||
VM_WARN_ON_ONCE(!rcu_read_lock_held());
|
||
|
||
do {
|
||
/* lru_gen_del_folio() has isolated this page? */
|
||
if (!(old_flags & LRU_GEN_MASK)) {
|
||
/* for shrink_folio_list() */
|
||
new_flags = old_flags | BIT(PG_referenced);
|
||
continue;
|
||
}
|
||
|
||
new_flags = old_flags & ~(LRU_GEN_MASK | LRU_REFS_MASK | LRU_REFS_FLAGS);
|
||
new_flags |= (gen + 1UL) << LRU_GEN_PGOFF;
|
||
} while (!try_cmpxchg(&folio->flags, &old_flags, new_flags));
|
||
|
||
return ((old_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
|
||
}
|
||
|
||
/* protect pages accessed multiple times through file descriptors */
|
||
static int folio_inc_gen(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
|
||
{
|
||
int type = folio_is_file_lru(folio);
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
int new_gen, old_gen = lru_gen_from_seq(lrugen->min_seq[type]);
|
||
unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(!(old_flags & LRU_GEN_MASK), folio);
|
||
|
||
do {
|
||
new_gen = ((old_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
|
||
/* folio_update_gen() has promoted this page? */
|
||
if (new_gen >= 0 && new_gen != old_gen)
|
||
return new_gen;
|
||
|
||
new_gen = (old_gen + 1) % MAX_NR_GENS;
|
||
|
||
new_flags = old_flags & ~(LRU_GEN_MASK | LRU_REFS_MASK | LRU_REFS_FLAGS);
|
||
new_flags |= (new_gen + 1UL) << LRU_GEN_PGOFF;
|
||
/* for folio_end_writeback() */
|
||
if (reclaiming)
|
||
new_flags |= BIT(PG_reclaim);
|
||
} while (!try_cmpxchg(&folio->flags, &old_flags, new_flags));
|
||
|
||
lru_gen_update_size(lruvec, folio, old_gen, new_gen);
|
||
|
||
return new_gen;
|
||
}
|
||
|
||
static void update_batch_size(struct lru_gen_mm_walk *walk, struct folio *folio,
|
||
int old_gen, int new_gen)
|
||
{
|
||
int type = folio_is_file_lru(folio);
|
||
int zone = folio_zonenum(folio);
|
||
int delta = folio_nr_pages(folio);
|
||
|
||
VM_WARN_ON_ONCE(old_gen >= MAX_NR_GENS);
|
||
VM_WARN_ON_ONCE(new_gen >= MAX_NR_GENS);
|
||
|
||
walk->batched++;
|
||
|
||
walk->nr_pages[old_gen][type][zone] -= delta;
|
||
walk->nr_pages[new_gen][type][zone] += delta;
|
||
}
|
||
|
||
static void reset_batch_size(struct lru_gen_mm_walk *walk)
|
||
{
|
||
int gen, type, zone;
|
||
struct lruvec *lruvec = walk->lruvec;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
|
||
walk->batched = 0;
|
||
|
||
for_each_gen_type_zone(gen, type, zone) {
|
||
enum lru_list lru = type * LRU_INACTIVE_FILE;
|
||
int delta = walk->nr_pages[gen][type][zone];
|
||
|
||
if (!delta)
|
||
continue;
|
||
|
||
walk->nr_pages[gen][type][zone] = 0;
|
||
WRITE_ONCE(lrugen->nr_pages[gen][type][zone],
|
||
lrugen->nr_pages[gen][type][zone] + delta);
|
||
|
||
if (lru_gen_is_active(lruvec, gen))
|
||
lru += LRU_ACTIVE;
|
||
__update_lru_size(lruvec, lru, zone, delta);
|
||
}
|
||
}
|
||
|
||
static int should_skip_vma(unsigned long start, unsigned long end, struct mm_walk *args)
|
||
{
|
||
struct address_space *mapping;
|
||
struct vm_area_struct *vma = args->vma;
|
||
struct lru_gen_mm_walk *walk = args->private;
|
||
|
||
if (!vma_is_accessible(vma))
|
||
return true;
|
||
|
||
if (is_vm_hugetlb_page(vma))
|
||
return true;
|
||
|
||
if (!vma_has_recency(vma))
|
||
return true;
|
||
|
||
if (vma->vm_flags & (VM_LOCKED | VM_SPECIAL))
|
||
return true;
|
||
|
||
if (vma == get_gate_vma(vma->vm_mm))
|
||
return true;
|
||
|
||
if (vma_is_anonymous(vma))
|
||
return !walk->can_swap;
|
||
|
||
if (WARN_ON_ONCE(!vma->vm_file || !vma->vm_file->f_mapping))
|
||
return true;
|
||
|
||
mapping = vma->vm_file->f_mapping;
|
||
if (mapping_unevictable(mapping))
|
||
return true;
|
||
|
||
if (shmem_mapping(mapping))
|
||
return !walk->can_swap;
|
||
|
||
/* to exclude special mappings like dax, etc. */
|
||
return !mapping->a_ops->read_folio;
|
||
}
|
||
|
||
/*
|
||
* Some userspace memory allocators map many single-page VMAs. Instead of
|
||
* returning back to the PGD table for each of such VMAs, finish an entire PMD
|
||
* table to reduce zigzags and improve cache performance.
|
||
*/
|
||
static bool get_next_vma(unsigned long mask, unsigned long size, struct mm_walk *args,
|
||
unsigned long *vm_start, unsigned long *vm_end)
|
||
{
|
||
unsigned long start = round_up(*vm_end, size);
|
||
unsigned long end = (start | ~mask) + 1;
|
||
VMA_ITERATOR(vmi, args->mm, start);
|
||
|
||
VM_WARN_ON_ONCE(mask & size);
|
||
VM_WARN_ON_ONCE((start & mask) != (*vm_start & mask));
|
||
|
||
for_each_vma(vmi, args->vma) {
|
||
if (end && end <= args->vma->vm_start)
|
||
return false;
|
||
|
||
if (should_skip_vma(args->vma->vm_start, args->vma->vm_end, args))
|
||
continue;
|
||
|
||
*vm_start = max(start, args->vma->vm_start);
|
||
*vm_end = min(end - 1, args->vma->vm_end - 1) + 1;
|
||
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
static unsigned long get_pte_pfn(pte_t pte, struct vm_area_struct *vma, unsigned long addr,
|
||
struct pglist_data *pgdat)
|
||
{
|
||
unsigned long pfn = pte_pfn(pte);
|
||
|
||
VM_WARN_ON_ONCE(addr < vma->vm_start || addr >= vma->vm_end);
|
||
|
||
if (!pte_present(pte) || is_zero_pfn(pfn))
|
||
return -1;
|
||
|
||
if (WARN_ON_ONCE(pte_devmap(pte) || pte_special(pte)))
|
||
return -1;
|
||
|
||
if (!pte_young(pte) && !mm_has_notifiers(vma->vm_mm))
|
||
return -1;
|
||
|
||
if (WARN_ON_ONCE(!pfn_valid(pfn)))
|
||
return -1;
|
||
|
||
if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat))
|
||
return -1;
|
||
|
||
return pfn;
|
||
}
|
||
|
||
static unsigned long get_pmd_pfn(pmd_t pmd, struct vm_area_struct *vma, unsigned long addr,
|
||
struct pglist_data *pgdat)
|
||
{
|
||
unsigned long pfn = pmd_pfn(pmd);
|
||
|
||
VM_WARN_ON_ONCE(addr < vma->vm_start || addr >= vma->vm_end);
|
||
|
||
if (!pmd_present(pmd) || is_huge_zero_pmd(pmd))
|
||
return -1;
|
||
|
||
if (WARN_ON_ONCE(pmd_devmap(pmd)))
|
||
return -1;
|
||
|
||
if (!pmd_young(pmd) && !mm_has_notifiers(vma->vm_mm))
|
||
return -1;
|
||
|
||
if (WARN_ON_ONCE(!pfn_valid(pfn)))
|
||
return -1;
|
||
|
||
if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat))
|
||
return -1;
|
||
|
||
return pfn;
|
||
}
|
||
|
||
static struct folio *get_pfn_folio(unsigned long pfn, struct mem_cgroup *memcg,
|
||
struct pglist_data *pgdat, bool can_swap)
|
||
{
|
||
struct folio *folio;
|
||
|
||
folio = pfn_folio(pfn);
|
||
if (folio_nid(folio) != pgdat->node_id)
|
||
return NULL;
|
||
|
||
if (folio_memcg_rcu(folio) != memcg)
|
||
return NULL;
|
||
|
||
/* file VMAs can contain anon pages from COW */
|
||
if (!folio_is_file_lru(folio) && !can_swap)
|
||
return NULL;
|
||
|
||
return folio;
|
||
}
|
||
|
||
static bool suitable_to_scan(int total, int young)
|
||
{
|
||
int n = clamp_t(int, cache_line_size() / sizeof(pte_t), 2, 8);
|
||
|
||
/* suitable if the average number of young PTEs per cacheline is >=1 */
|
||
return young * n >= total;
|
||
}
|
||
|
||
static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end,
|
||
struct mm_walk *args)
|
||
{
|
||
int i;
|
||
pte_t *pte;
|
||
spinlock_t *ptl;
|
||
unsigned long addr;
|
||
int total = 0;
|
||
int young = 0;
|
||
struct lru_gen_mm_walk *walk = args->private;
|
||
struct mem_cgroup *memcg = lruvec_memcg(walk->lruvec);
|
||
struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
|
||
DEFINE_MAX_SEQ(walk->lruvec);
|
||
int old_gen, new_gen = lru_gen_from_seq(max_seq);
|
||
|
||
pte = pte_offset_map_nolock(args->mm, pmd, start & PMD_MASK, &ptl);
|
||
if (!pte)
|
||
return false;
|
||
if (!spin_trylock(ptl)) {
|
||
pte_unmap(pte);
|
||
return false;
|
||
}
|
||
|
||
arch_enter_lazy_mmu_mode();
|
||
restart:
|
||
for (i = pte_index(start), addr = start; addr != end; i++, addr += PAGE_SIZE) {
|
||
unsigned long pfn;
|
||
struct folio *folio;
|
||
pte_t ptent = ptep_get(pte + i);
|
||
|
||
total++;
|
||
walk->mm_stats[MM_LEAF_TOTAL]++;
|
||
|
||
pfn = get_pte_pfn(ptent, args->vma, addr, pgdat);
|
||
if (pfn == -1)
|
||
continue;
|
||
|
||
folio = get_pfn_folio(pfn, memcg, pgdat, walk->can_swap);
|
||
if (!folio)
|
||
continue;
|
||
|
||
if (!ptep_clear_young_notify(args->vma, addr, pte + i))
|
||
continue;
|
||
|
||
young++;
|
||
walk->mm_stats[MM_LEAF_YOUNG]++;
|
||
|
||
if (pte_dirty(ptent) && !folio_test_dirty(folio) &&
|
||
!(folio_test_anon(folio) && folio_test_swapbacked(folio) &&
|
||
!folio_test_swapcache(folio)))
|
||
folio_mark_dirty(folio);
|
||
|
||
old_gen = folio_update_gen(folio, new_gen);
|
||
if (old_gen >= 0 && old_gen != new_gen)
|
||
update_batch_size(walk, folio, old_gen, new_gen);
|
||
}
|
||
|
||
if (i < PTRS_PER_PTE && get_next_vma(PMD_MASK, PAGE_SIZE, args, &start, &end))
|
||
goto restart;
|
||
|
||
arch_leave_lazy_mmu_mode();
|
||
pte_unmap_unlock(pte, ptl);
|
||
|
||
return suitable_to_scan(total, young);
|
||
}
|
||
|
||
static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area_struct *vma,
|
||
struct mm_walk *args, unsigned long *bitmap, unsigned long *first)
|
||
{
|
||
int i;
|
||
pmd_t *pmd;
|
||
spinlock_t *ptl;
|
||
struct lru_gen_mm_walk *walk = args->private;
|
||
struct mem_cgroup *memcg = lruvec_memcg(walk->lruvec);
|
||
struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
|
||
DEFINE_MAX_SEQ(walk->lruvec);
|
||
int old_gen, new_gen = lru_gen_from_seq(max_seq);
|
||
|
||
VM_WARN_ON_ONCE(pud_leaf(*pud));
|
||
|
||
/* try to batch at most 1+MIN_LRU_BATCH+1 entries */
|
||
if (*first == -1) {
|
||
*first = addr;
|
||
bitmap_zero(bitmap, MIN_LRU_BATCH);
|
||
return;
|
||
}
|
||
|
||
i = addr == -1 ? 0 : pmd_index(addr) - pmd_index(*first);
|
||
if (i && i <= MIN_LRU_BATCH) {
|
||
__set_bit(i - 1, bitmap);
|
||
return;
|
||
}
|
||
|
||
pmd = pmd_offset(pud, *first);
|
||
|
||
ptl = pmd_lockptr(args->mm, pmd);
|
||
if (!spin_trylock(ptl))
|
||
goto done;
|
||
|
||
arch_enter_lazy_mmu_mode();
|
||
|
||
do {
|
||
unsigned long pfn;
|
||
struct folio *folio;
|
||
|
||
/* don't round down the first address */
|
||
addr = i ? (*first & PMD_MASK) + i * PMD_SIZE : *first;
|
||
|
||
if (!pmd_present(pmd[i]))
|
||
goto next;
|
||
|
||
if (!pmd_trans_huge(pmd[i])) {
|
||
if (!walk->force_scan && should_clear_pmd_young() &&
|
||
!mm_has_notifiers(args->mm))
|
||
pmdp_test_and_clear_young(vma, addr, pmd + i);
|
||
goto next;
|
||
}
|
||
|
||
pfn = get_pmd_pfn(pmd[i], vma, addr, pgdat);
|
||
if (pfn == -1)
|
||
goto next;
|
||
|
||
folio = get_pfn_folio(pfn, memcg, pgdat, walk->can_swap);
|
||
if (!folio)
|
||
goto next;
|
||
|
||
if (!pmdp_clear_young_notify(vma, addr, pmd + i))
|
||
goto next;
|
||
|
||
walk->mm_stats[MM_LEAF_YOUNG]++;
|
||
|
||
if (pmd_dirty(pmd[i]) && !folio_test_dirty(folio) &&
|
||
!(folio_test_anon(folio) && folio_test_swapbacked(folio) &&
|
||
!folio_test_swapcache(folio)))
|
||
folio_mark_dirty(folio);
|
||
|
||
old_gen = folio_update_gen(folio, new_gen);
|
||
if (old_gen >= 0 && old_gen != new_gen)
|
||
update_batch_size(walk, folio, old_gen, new_gen);
|
||
next:
|
||
i = i > MIN_LRU_BATCH ? 0 : find_next_bit(bitmap, MIN_LRU_BATCH, i) + 1;
|
||
} while (i <= MIN_LRU_BATCH);
|
||
|
||
arch_leave_lazy_mmu_mode();
|
||
spin_unlock(ptl);
|
||
done:
|
||
*first = -1;
|
||
}
|
||
|
||
static void walk_pmd_range(pud_t *pud, unsigned long start, unsigned long end,
|
||
struct mm_walk *args)
|
||
{
|
||
int i;
|
||
pmd_t *pmd;
|
||
unsigned long next;
|
||
unsigned long addr;
|
||
struct vm_area_struct *vma;
|
||
DECLARE_BITMAP(bitmap, MIN_LRU_BATCH);
|
||
unsigned long first = -1;
|
||
struct lru_gen_mm_walk *walk = args->private;
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(walk->lruvec);
|
||
|
||
VM_WARN_ON_ONCE(pud_leaf(*pud));
|
||
|
||
/*
|
||
* Finish an entire PMD in two passes: the first only reaches to PTE
|
||
* tables to avoid taking the PMD lock; the second, if necessary, takes
|
||
* the PMD lock to clear the accessed bit in PMD entries.
|
||
*/
|
||
pmd = pmd_offset(pud, start & PUD_MASK);
|
||
restart:
|
||
/* walk_pte_range() may call get_next_vma() */
|
||
vma = args->vma;
|
||
for (i = pmd_index(start), addr = start; addr != end; i++, addr = next) {
|
||
pmd_t val = pmdp_get_lockless(pmd + i);
|
||
|
||
next = pmd_addr_end(addr, end);
|
||
|
||
if (!pmd_present(val) || is_huge_zero_pmd(val)) {
|
||
walk->mm_stats[MM_LEAF_TOTAL]++;
|
||
continue;
|
||
}
|
||
|
||
if (pmd_trans_huge(val)) {
|
||
struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
|
||
unsigned long pfn = get_pmd_pfn(val, vma, addr, pgdat);
|
||
|
||
walk->mm_stats[MM_LEAF_TOTAL]++;
|
||
|
||
if (pfn != -1)
|
||
walk_pmd_range_locked(pud, addr, vma, args, bitmap, &first);
|
||
continue;
|
||
}
|
||
|
||
if (!walk->force_scan && should_clear_pmd_young() &&
|
||
!mm_has_notifiers(args->mm)) {
|
||
if (!pmd_young(val))
|
||
continue;
|
||
|
||
walk_pmd_range_locked(pud, addr, vma, args, bitmap, &first);
|
||
}
|
||
|
||
if (!walk->force_scan && !test_bloom_filter(mm_state, walk->seq, pmd + i))
|
||
continue;
|
||
|
||
walk->mm_stats[MM_NONLEAF_FOUND]++;
|
||
|
||
if (!walk_pte_range(&val, addr, next, args))
|
||
continue;
|
||
|
||
walk->mm_stats[MM_NONLEAF_ADDED]++;
|
||
|
||
/* carry over to the next generation */
|
||
update_bloom_filter(mm_state, walk->seq + 1, pmd + i);
|
||
}
|
||
|
||
walk_pmd_range_locked(pud, -1, vma, args, bitmap, &first);
|
||
|
||
if (i < PTRS_PER_PMD && get_next_vma(PUD_MASK, PMD_SIZE, args, &start, &end))
|
||
goto restart;
|
||
}
|
||
|
||
static int walk_pud_range(p4d_t *p4d, unsigned long start, unsigned long end,
|
||
struct mm_walk *args)
|
||
{
|
||
int i;
|
||
pud_t *pud;
|
||
unsigned long addr;
|
||
unsigned long next;
|
||
struct lru_gen_mm_walk *walk = args->private;
|
||
|
||
VM_WARN_ON_ONCE(p4d_leaf(*p4d));
|
||
|
||
pud = pud_offset(p4d, start & P4D_MASK);
|
||
restart:
|
||
for (i = pud_index(start), addr = start; addr != end; i++, addr = next) {
|
||
pud_t val = READ_ONCE(pud[i]);
|
||
|
||
next = pud_addr_end(addr, end);
|
||
|
||
if (!pud_present(val) || WARN_ON_ONCE(pud_leaf(val)))
|
||
continue;
|
||
|
||
walk_pmd_range(&val, addr, next, args);
|
||
|
||
if (need_resched() || walk->batched >= MAX_LRU_BATCH) {
|
||
end = (addr | ~PUD_MASK) + 1;
|
||
goto done;
|
||
}
|
||
}
|
||
|
||
if (i < PTRS_PER_PUD && get_next_vma(P4D_MASK, PUD_SIZE, args, &start, &end))
|
||
goto restart;
|
||
|
||
end = round_up(end, P4D_SIZE);
|
||
done:
|
||
if (!end || !args->vma)
|
||
return 1;
|
||
|
||
walk->next_addr = max(end, args->vma->vm_start);
|
||
|
||
return -EAGAIN;
|
||
}
|
||
|
||
static void walk_mm(struct mm_struct *mm, struct lru_gen_mm_walk *walk)
|
||
{
|
||
static const struct mm_walk_ops mm_walk_ops = {
|
||
.test_walk = should_skip_vma,
|
||
.p4d_entry = walk_pud_range,
|
||
.walk_lock = PGWALK_RDLOCK,
|
||
};
|
||
|
||
int err;
|
||
struct lruvec *lruvec = walk->lruvec;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
|
||
walk->next_addr = FIRST_USER_ADDRESS;
|
||
|
||
do {
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
|
||
err = -EBUSY;
|
||
|
||
/* another thread might have called inc_max_seq() */
|
||
if (walk->seq != max_seq)
|
||
break;
|
||
|
||
/* folio_update_gen() requires stable folio_memcg() */
|
||
if (!mem_cgroup_trylock_pages(memcg))
|
||
break;
|
||
|
||
/* the caller might be holding the lock for write */
|
||
if (mmap_read_trylock(mm)) {
|
||
err = walk_page_range(mm, walk->next_addr, ULONG_MAX, &mm_walk_ops, walk);
|
||
|
||
mmap_read_unlock(mm);
|
||
}
|
||
|
||
mem_cgroup_unlock_pages();
|
||
|
||
if (walk->batched) {
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
reset_batch_size(walk);
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
}
|
||
|
||
cond_resched();
|
||
} while (err == -EAGAIN);
|
||
}
|
||
|
||
static struct lru_gen_mm_walk *set_mm_walk(struct pglist_data *pgdat, bool force_alloc)
|
||
{
|
||
struct lru_gen_mm_walk *walk = current->reclaim_state->mm_walk;
|
||
|
||
if (pgdat && current_is_kswapd()) {
|
||
VM_WARN_ON_ONCE(walk);
|
||
|
||
walk = &pgdat->mm_walk;
|
||
} else if (!walk && force_alloc) {
|
||
VM_WARN_ON_ONCE(current_is_kswapd());
|
||
|
||
walk = kzalloc(sizeof(*walk), __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN);
|
||
}
|
||
|
||
current->reclaim_state->mm_walk = walk;
|
||
|
||
return walk;
|
||
}
|
||
|
||
static void clear_mm_walk(void)
|
||
{
|
||
struct lru_gen_mm_walk *walk = current->reclaim_state->mm_walk;
|
||
|
||
VM_WARN_ON_ONCE(walk && memchr_inv(walk->nr_pages, 0, sizeof(walk->nr_pages)));
|
||
VM_WARN_ON_ONCE(walk && memchr_inv(walk->mm_stats, 0, sizeof(walk->mm_stats)));
|
||
|
||
current->reclaim_state->mm_walk = NULL;
|
||
|
||
if (!current_is_kswapd())
|
||
kfree(walk);
|
||
}
|
||
|
||
static bool inc_min_seq(struct lruvec *lruvec, int type, bool can_swap)
|
||
{
|
||
int zone;
|
||
int remaining = MAX_LRU_BATCH;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
int new_gen, old_gen = lru_gen_from_seq(lrugen->min_seq[type]);
|
||
|
||
if (type == LRU_GEN_ANON && !can_swap)
|
||
goto done;
|
||
|
||
/* prevent cold/hot inversion if force_scan is true */
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
|
||
struct list_head *head = &lrugen->folios[old_gen][type][zone];
|
||
|
||
while (!list_empty(head)) {
|
||
struct folio *folio = lru_to_folio(head);
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio);
|
||
|
||
new_gen = folio_inc_gen(lruvec, folio, false);
|
||
list_move_tail(&folio->lru, &lrugen->folios[new_gen][type][zone]);
|
||
|
||
if (!--remaining)
|
||
return false;
|
||
}
|
||
}
|
||
done:
|
||
reset_ctrl_pos(lruvec, type, true);
|
||
WRITE_ONCE(lrugen->min_seq[type], lrugen->min_seq[type] + 1);
|
||
|
||
return true;
|
||
}
|
||
|
||
static bool try_to_inc_min_seq(struct lruvec *lruvec, bool can_swap)
|
||
{
|
||
int gen, type, zone;
|
||
bool success = false;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
|
||
|
||
/* find the oldest populated generation */
|
||
for (type = !can_swap; type < ANON_AND_FILE; type++) {
|
||
while (min_seq[type] + MIN_NR_GENS <= lrugen->max_seq) {
|
||
gen = lru_gen_from_seq(min_seq[type]);
|
||
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
|
||
if (!list_empty(&lrugen->folios[gen][type][zone]))
|
||
goto next;
|
||
}
|
||
|
||
min_seq[type]++;
|
||
}
|
||
next:
|
||
;
|
||
}
|
||
|
||
/* see the comment on lru_gen_folio */
|
||
if (can_swap) {
|
||
min_seq[LRU_GEN_ANON] = min(min_seq[LRU_GEN_ANON], min_seq[LRU_GEN_FILE]);
|
||
min_seq[LRU_GEN_FILE] = max(min_seq[LRU_GEN_ANON], lrugen->min_seq[LRU_GEN_FILE]);
|
||
}
|
||
|
||
for (type = !can_swap; type < ANON_AND_FILE; type++) {
|
||
if (min_seq[type] == lrugen->min_seq[type])
|
||
continue;
|
||
|
||
reset_ctrl_pos(lruvec, type, true);
|
||
WRITE_ONCE(lrugen->min_seq[type], min_seq[type]);
|
||
success = true;
|
||
}
|
||
|
||
return success;
|
||
}
|
||
|
||
static bool inc_max_seq(struct lruvec *lruvec, unsigned long seq,
|
||
bool can_swap, bool force_scan)
|
||
{
|
||
bool success;
|
||
int prev, next;
|
||
int type, zone;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
restart:
|
||
if (seq < READ_ONCE(lrugen->max_seq))
|
||
return false;
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
|
||
|
||
success = seq == lrugen->max_seq;
|
||
if (!success)
|
||
goto unlock;
|
||
|
||
for (type = ANON_AND_FILE - 1; type >= 0; type--) {
|
||
if (get_nr_gens(lruvec, type) != MAX_NR_GENS)
|
||
continue;
|
||
|
||
VM_WARN_ON_ONCE(!force_scan && (type == LRU_GEN_FILE || can_swap));
|
||
|
||
if (inc_min_seq(lruvec, type, can_swap))
|
||
continue;
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
cond_resched();
|
||
goto restart;
|
||
}
|
||
|
||
/*
|
||
* Update the active/inactive LRU sizes for compatibility. Both sides of
|
||
* the current max_seq need to be covered, since max_seq+1 can overlap
|
||
* with min_seq[LRU_GEN_ANON] if swapping is constrained. And if they do
|
||
* overlap, cold/hot inversion happens.
|
||
*/
|
||
prev = lru_gen_from_seq(lrugen->max_seq - 1);
|
||
next = lru_gen_from_seq(lrugen->max_seq + 1);
|
||
|
||
for (type = 0; type < ANON_AND_FILE; type++) {
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
|
||
enum lru_list lru = type * LRU_INACTIVE_FILE;
|
||
long delta = lrugen->nr_pages[prev][type][zone] -
|
||
lrugen->nr_pages[next][type][zone];
|
||
|
||
if (!delta)
|
||
continue;
|
||
|
||
__update_lru_size(lruvec, lru, zone, delta);
|
||
__update_lru_size(lruvec, lru + LRU_ACTIVE, zone, -delta);
|
||
}
|
||
}
|
||
|
||
for (type = 0; type < ANON_AND_FILE; type++)
|
||
reset_ctrl_pos(lruvec, type, false);
|
||
|
||
WRITE_ONCE(lrugen->timestamps[next], jiffies);
|
||
/* make sure preceding modifications appear */
|
||
smp_store_release(&lrugen->max_seq, lrugen->max_seq + 1);
|
||
unlock:
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
return success;
|
||
}
|
||
|
||
static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long seq,
|
||
bool can_swap, bool force_scan)
|
||
{
|
||
bool success;
|
||
struct lru_gen_mm_walk *walk;
|
||
struct mm_struct *mm = NULL;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
VM_WARN_ON_ONCE(seq > READ_ONCE(lrugen->max_seq));
|
||
|
||
if (!mm_state)
|
||
return inc_max_seq(lruvec, seq, can_swap, force_scan);
|
||
|
||
/* see the comment in iterate_mm_list() */
|
||
if (seq <= READ_ONCE(mm_state->seq))
|
||
return false;
|
||
|
||
/*
|
||
* If the hardware doesn't automatically set the accessed bit, fallback
|
||
* to lru_gen_look_around(), which only clears the accessed bit in a
|
||
* handful of PTEs. Spreading the work out over a period of time usually
|
||
* is less efficient, but it avoids bursty page faults.
|
||
*/
|
||
if (!should_walk_mmu()) {
|
||
success = iterate_mm_list_nowalk(lruvec, seq);
|
||
goto done;
|
||
}
|
||
|
||
walk = set_mm_walk(NULL, true);
|
||
if (!walk) {
|
||
success = iterate_mm_list_nowalk(lruvec, seq);
|
||
goto done;
|
||
}
|
||
|
||
walk->lruvec = lruvec;
|
||
walk->seq = seq;
|
||
walk->can_swap = can_swap;
|
||
walk->force_scan = force_scan;
|
||
|
||
do {
|
||
success = iterate_mm_list(walk, &mm);
|
||
if (mm)
|
||
walk_mm(mm, walk);
|
||
} while (mm);
|
||
done:
|
||
if (success) {
|
||
success = inc_max_seq(lruvec, seq, can_swap, force_scan);
|
||
WARN_ON_ONCE(!success);
|
||
}
|
||
|
||
return success;
|
||
}
|
||
|
||
/******************************************************************************
|
||
* working set protection
|
||
******************************************************************************/
|
||
|
||
static void set_initial_priority(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
int priority;
|
||
unsigned long reclaimable;
|
||
|
||
if (sc->priority != DEF_PRIORITY || sc->nr_to_reclaim < MIN_LRU_BATCH)
|
||
return;
|
||
/*
|
||
* Determine the initial priority based on
|
||
* (total >> priority) * reclaimed_to_scanned_ratio = nr_to_reclaim,
|
||
* where reclaimed_to_scanned_ratio = inactive / total.
|
||
*/
|
||
reclaimable = node_page_state(pgdat, NR_INACTIVE_FILE);
|
||
if (can_reclaim_anon_pages(NULL, pgdat->node_id, sc))
|
||
reclaimable += node_page_state(pgdat, NR_INACTIVE_ANON);
|
||
|
||
/* round down reclaimable and round up sc->nr_to_reclaim */
|
||
priority = fls_long(reclaimable) - 1 - fls_long(sc->nr_to_reclaim - 1);
|
||
|
||
/*
|
||
* The estimation is based on LRU pages only, so cap it to prevent
|
||
* overshoots of shrinker objects by large margins.
|
||
*/
|
||
sc->priority = clamp(priority, DEF_PRIORITY / 2, DEF_PRIORITY);
|
||
}
|
||
|
||
static bool lruvec_is_sizable(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
int gen, type, zone;
|
||
unsigned long total = 0;
|
||
bool can_swap = get_swappiness(lruvec, sc);
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
for (type = !can_swap; type < ANON_AND_FILE; type++) {
|
||
unsigned long seq;
|
||
|
||
for (seq = min_seq[type]; seq <= max_seq; seq++) {
|
||
gen = lru_gen_from_seq(seq);
|
||
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++)
|
||
total += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
|
||
}
|
||
}
|
||
|
||
/* whether the size is big enough to be helpful */
|
||
return mem_cgroup_online(memcg) ? (total >> sc->priority) : total;
|
||
}
|
||
|
||
static bool lruvec_is_reclaimable(struct lruvec *lruvec, struct scan_control *sc,
|
||
unsigned long min_ttl)
|
||
{
|
||
int gen;
|
||
unsigned long birth;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
if (mem_cgroup_below_min(NULL, memcg))
|
||
return false;
|
||
|
||
if (!lruvec_is_sizable(lruvec, sc))
|
||
return false;
|
||
|
||
/* see the comment on lru_gen_folio */
|
||
gen = lru_gen_from_seq(min_seq[LRU_GEN_FILE]);
|
||
birth = READ_ONCE(lruvec->lrugen.timestamps[gen]);
|
||
|
||
return time_is_before_jiffies(birth + min_ttl);
|
||
}
|
||
|
||
/* to protect the working set of the last N jiffies */
|
||
static unsigned long lru_gen_min_ttl __read_mostly;
|
||
|
||
static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
struct mem_cgroup *memcg;
|
||
unsigned long min_ttl = READ_ONCE(lru_gen_min_ttl);
|
||
bool reclaimable = !min_ttl;
|
||
|
||
VM_WARN_ON_ONCE(!current_is_kswapd());
|
||
|
||
set_initial_priority(pgdat, sc);
|
||
|
||
memcg = mem_cgroup_iter(NULL, NULL, NULL);
|
||
do {
|
||
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
|
||
|
||
mem_cgroup_calculate_protection(NULL, memcg);
|
||
|
||
if (!reclaimable)
|
||
reclaimable = lruvec_is_reclaimable(lruvec, sc, min_ttl);
|
||
} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)));
|
||
|
||
/*
|
||
* The main goal is to OOM kill if every generation from all memcgs is
|
||
* younger than min_ttl. However, another possibility is all memcgs are
|
||
* either too small or below min.
|
||
*/
|
||
if (!reclaimable && mutex_trylock(&oom_lock)) {
|
||
struct oom_control oc = {
|
||
.gfp_mask = sc->gfp_mask,
|
||
};
|
||
|
||
out_of_memory(&oc);
|
||
|
||
mutex_unlock(&oom_lock);
|
||
}
|
||
}
|
||
|
||
/******************************************************************************
|
||
* rmap/PT walk feedback
|
||
******************************************************************************/
|
||
|
||
/*
|
||
* This function exploits spatial locality when shrink_folio_list() walks the
|
||
* rmap. It scans the adjacent PTEs of a young PTE and promotes hot pages. If
|
||
* the scan was done cacheline efficiently, it adds the PMD entry pointing to
|
||
* the PTE table to the Bloom filter. This forms a feedback loop between the
|
||
* eviction and the aging.
|
||
*/
|
||
bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw)
|
||
{
|
||
int i;
|
||
unsigned long start;
|
||
unsigned long end;
|
||
struct lru_gen_mm_walk *walk;
|
||
int young = 1;
|
||
pte_t *pte = pvmw->pte;
|
||
unsigned long addr = pvmw->address;
|
||
struct vm_area_struct *vma = pvmw->vma;
|
||
struct folio *folio = pfn_folio(pvmw->pfn);
|
||
bool can_swap = !folio_is_file_lru(folio);
|
||
struct mem_cgroup *memcg = folio_memcg(folio);
|
||
struct pglist_data *pgdat = folio_pgdat(folio);
|
||
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
int old_gen, new_gen = lru_gen_from_seq(max_seq);
|
||
|
||
lockdep_assert_held(pvmw->ptl);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_lru(folio), folio);
|
||
|
||
if (!ptep_clear_young_notify(vma, addr, pte))
|
||
return false;
|
||
|
||
if (spin_is_contended(pvmw->ptl))
|
||
return true;
|
||
|
||
/* exclude special VMAs containing anon pages from COW */
|
||
if (vma->vm_flags & VM_SPECIAL)
|
||
return true;
|
||
|
||
/* avoid taking the LRU lock under the PTL when possible */
|
||
walk = current->reclaim_state ? current->reclaim_state->mm_walk : NULL;
|
||
|
||
start = max(addr & PMD_MASK, vma->vm_start);
|
||
end = min(addr | ~PMD_MASK, vma->vm_end - 1) + 1;
|
||
|
||
if (end - start == PAGE_SIZE)
|
||
return true;
|
||
|
||
if (end - start > MIN_LRU_BATCH * PAGE_SIZE) {
|
||
if (addr - start < MIN_LRU_BATCH * PAGE_SIZE / 2)
|
||
end = start + MIN_LRU_BATCH * PAGE_SIZE;
|
||
else if (end - addr < MIN_LRU_BATCH * PAGE_SIZE / 2)
|
||
start = end - MIN_LRU_BATCH * PAGE_SIZE;
|
||
else {
|
||
start = addr - MIN_LRU_BATCH * PAGE_SIZE / 2;
|
||
end = addr + MIN_LRU_BATCH * PAGE_SIZE / 2;
|
||
}
|
||
}
|
||
|
||
/* folio_update_gen() requires stable folio_memcg() */
|
||
if (!mem_cgroup_trylock_pages(memcg))
|
||
return true;
|
||
|
||
arch_enter_lazy_mmu_mode();
|
||
|
||
pte -= (addr - start) / PAGE_SIZE;
|
||
|
||
for (i = 0, addr = start; addr != end; i++, addr += PAGE_SIZE) {
|
||
unsigned long pfn;
|
||
pte_t ptent = ptep_get(pte + i);
|
||
|
||
pfn = get_pte_pfn(ptent, vma, addr, pgdat);
|
||
if (pfn == -1)
|
||
continue;
|
||
|
||
folio = get_pfn_folio(pfn, memcg, pgdat, can_swap);
|
||
if (!folio)
|
||
continue;
|
||
|
||
if (!ptep_clear_young_notify(vma, addr, pte + i))
|
||
continue;
|
||
|
||
young++;
|
||
|
||
if (pte_dirty(ptent) && !folio_test_dirty(folio) &&
|
||
!(folio_test_anon(folio) && folio_test_swapbacked(folio) &&
|
||
!folio_test_swapcache(folio)))
|
||
folio_mark_dirty(folio);
|
||
|
||
if (walk) {
|
||
old_gen = folio_update_gen(folio, new_gen);
|
||
if (old_gen >= 0 && old_gen != new_gen)
|
||
update_batch_size(walk, folio, old_gen, new_gen);
|
||
|
||
continue;
|
||
}
|
||
|
||
old_gen = folio_lru_gen(folio);
|
||
if (old_gen < 0)
|
||
folio_set_referenced(folio);
|
||
else if (old_gen != new_gen)
|
||
folio_activate(folio);
|
||
}
|
||
|
||
arch_leave_lazy_mmu_mode();
|
||
mem_cgroup_unlock_pages();
|
||
|
||
/* feedback from rmap walkers to page table walkers */
|
||
if (mm_state && suitable_to_scan(i, young))
|
||
update_bloom_filter(mm_state, max_seq, pvmw->pmd);
|
||
|
||
return true;
|
||
}
|
||
|
||
/******************************************************************************
|
||
* memcg LRU
|
||
******************************************************************************/
|
||
|
||
/* see the comment on MEMCG_NR_GENS */
|
||
enum {
|
||
MEMCG_LRU_NOP,
|
||
MEMCG_LRU_HEAD,
|
||
MEMCG_LRU_TAIL,
|
||
MEMCG_LRU_OLD,
|
||
MEMCG_LRU_YOUNG,
|
||
};
|
||
|
||
static void lru_gen_rotate_memcg(struct lruvec *lruvec, int op)
|
||
{
|
||
int seg;
|
||
int old, new;
|
||
unsigned long flags;
|
||
int bin = get_random_u32_below(MEMCG_NR_BINS);
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
|
||
spin_lock_irqsave(&pgdat->memcg_lru.lock, flags);
|
||
|
||
VM_WARN_ON_ONCE(hlist_nulls_unhashed(&lruvec->lrugen.list));
|
||
|
||
seg = 0;
|
||
new = old = lruvec->lrugen.gen;
|
||
|
||
/* see the comment on MEMCG_NR_GENS */
|
||
if (op == MEMCG_LRU_HEAD)
|
||
seg = MEMCG_LRU_HEAD;
|
||
else if (op == MEMCG_LRU_TAIL)
|
||
seg = MEMCG_LRU_TAIL;
|
||
else if (op == MEMCG_LRU_OLD)
|
||
new = get_memcg_gen(pgdat->memcg_lru.seq);
|
||
else if (op == MEMCG_LRU_YOUNG)
|
||
new = get_memcg_gen(pgdat->memcg_lru.seq + 1);
|
||
else
|
||
VM_WARN_ON_ONCE(true);
|
||
|
||
WRITE_ONCE(lruvec->lrugen.seg, seg);
|
||
WRITE_ONCE(lruvec->lrugen.gen, new);
|
||
|
||
hlist_nulls_del_rcu(&lruvec->lrugen.list);
|
||
|
||
if (op == MEMCG_LRU_HEAD || op == MEMCG_LRU_OLD)
|
||
hlist_nulls_add_head_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[new][bin]);
|
||
else
|
||
hlist_nulls_add_tail_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[new][bin]);
|
||
|
||
pgdat->memcg_lru.nr_memcgs[old]--;
|
||
pgdat->memcg_lru.nr_memcgs[new]++;
|
||
|
||
if (!pgdat->memcg_lru.nr_memcgs[old] && old == get_memcg_gen(pgdat->memcg_lru.seq))
|
||
WRITE_ONCE(pgdat->memcg_lru.seq, pgdat->memcg_lru.seq + 1);
|
||
|
||
spin_unlock_irqrestore(&pgdat->memcg_lru.lock, flags);
|
||
}
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
|
||
void lru_gen_online_memcg(struct mem_cgroup *memcg)
|
||
{
|
||
int gen;
|
||
int nid;
|
||
int bin = get_random_u32_below(MEMCG_NR_BINS);
|
||
|
||
for_each_node(nid) {
|
||
struct pglist_data *pgdat = NODE_DATA(nid);
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
|
||
spin_lock_irq(&pgdat->memcg_lru.lock);
|
||
|
||
VM_WARN_ON_ONCE(!hlist_nulls_unhashed(&lruvec->lrugen.list));
|
||
|
||
gen = get_memcg_gen(pgdat->memcg_lru.seq);
|
||
|
||
lruvec->lrugen.gen = gen;
|
||
|
||
hlist_nulls_add_tail_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[gen][bin]);
|
||
pgdat->memcg_lru.nr_memcgs[gen]++;
|
||
|
||
spin_unlock_irq(&pgdat->memcg_lru.lock);
|
||
}
|
||
}
|
||
|
||
void lru_gen_offline_memcg(struct mem_cgroup *memcg)
|
||
{
|
||
int nid;
|
||
|
||
for_each_node(nid) {
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
|
||
lru_gen_rotate_memcg(lruvec, MEMCG_LRU_OLD);
|
||
}
|
||
}
|
||
|
||
void lru_gen_release_memcg(struct mem_cgroup *memcg)
|
||
{
|
||
int gen;
|
||
int nid;
|
||
|
||
for_each_node(nid) {
|
||
struct pglist_data *pgdat = NODE_DATA(nid);
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
|
||
spin_lock_irq(&pgdat->memcg_lru.lock);
|
||
|
||
if (hlist_nulls_unhashed(&lruvec->lrugen.list))
|
||
goto unlock;
|
||
|
||
gen = lruvec->lrugen.gen;
|
||
|
||
hlist_nulls_del_init_rcu(&lruvec->lrugen.list);
|
||
pgdat->memcg_lru.nr_memcgs[gen]--;
|
||
|
||
if (!pgdat->memcg_lru.nr_memcgs[gen] && gen == get_memcg_gen(pgdat->memcg_lru.seq))
|
||
WRITE_ONCE(pgdat->memcg_lru.seq, pgdat->memcg_lru.seq + 1);
|
||
unlock:
|
||
spin_unlock_irq(&pgdat->memcg_lru.lock);
|
||
}
|
||
}
|
||
|
||
void lru_gen_soft_reclaim(struct mem_cgroup *memcg, int nid)
|
||
{
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
|
||
/* see the comment on MEMCG_NR_GENS */
|
||
if (READ_ONCE(lruvec->lrugen.seg) != MEMCG_LRU_HEAD)
|
||
lru_gen_rotate_memcg(lruvec, MEMCG_LRU_HEAD);
|
||
}
|
||
|
||
#endif /* CONFIG_MEMCG */
|
||
|
||
/******************************************************************************
|
||
* the eviction
|
||
******************************************************************************/
|
||
|
||
static bool sort_folio(struct lruvec *lruvec, struct folio *folio, struct scan_control *sc,
|
||
int tier_idx)
|
||
{
|
||
bool success;
|
||
int gen = folio_lru_gen(folio);
|
||
int type = folio_is_file_lru(folio);
|
||
int zone = folio_zonenum(folio);
|
||
int delta = folio_nr_pages(folio);
|
||
int refs = folio_lru_refs(folio);
|
||
int tier = lru_tier_from_refs(refs);
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(gen >= MAX_NR_GENS, folio);
|
||
|
||
/* unevictable */
|
||
if (!folio_evictable(folio)) {
|
||
success = lru_gen_del_folio(lruvec, folio, true);
|
||
VM_WARN_ON_ONCE_FOLIO(!success, folio);
|
||
folio_set_unevictable(folio);
|
||
lruvec_add_folio(lruvec, folio);
|
||
__count_vm_events(UNEVICTABLE_PGCULLED, delta);
|
||
return true;
|
||
}
|
||
|
||
/* promoted */
|
||
if (gen != lru_gen_from_seq(lrugen->min_seq[type])) {
|
||
list_move(&folio->lru, &lrugen->folios[gen][type][zone]);
|
||
return true;
|
||
}
|
||
|
||
/* protected */
|
||
if (tier > tier_idx || refs == BIT(LRU_REFS_WIDTH)) {
|
||
int hist = lru_hist_from_seq(lrugen->min_seq[type]);
|
||
|
||
gen = folio_inc_gen(lruvec, folio, false);
|
||
list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]);
|
||
|
||
WRITE_ONCE(lrugen->protected[hist][type][tier - 1],
|
||
lrugen->protected[hist][type][tier - 1] + delta);
|
||
return true;
|
||
}
|
||
|
||
/* ineligible */
|
||
if (!folio_test_lru(folio) || zone > sc->reclaim_idx) {
|
||
gen = folio_inc_gen(lruvec, folio, false);
|
||
list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]);
|
||
return true;
|
||
}
|
||
|
||
/* waiting for writeback */
|
||
if (folio_test_locked(folio) || folio_test_writeback(folio) ||
|
||
(type == LRU_GEN_FILE && folio_test_dirty(folio))) {
|
||
gen = folio_inc_gen(lruvec, folio, true);
|
||
list_move(&folio->lru, &lrugen->folios[gen][type][zone]);
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
static bool isolate_folio(struct lruvec *lruvec, struct folio *folio, struct scan_control *sc)
|
||
{
|
||
bool success;
|
||
|
||
/* swap constrained */
|
||
if (!(sc->gfp_mask & __GFP_IO) &&
|
||
(folio_test_dirty(folio) ||
|
||
(folio_test_anon(folio) && !folio_test_swapcache(folio))))
|
||
return false;
|
||
|
||
/* raced with release_pages() */
|
||
if (!folio_try_get(folio))
|
||
return false;
|
||
|
||
/* raced with another isolation */
|
||
if (!folio_test_clear_lru(folio)) {
|
||
folio_put(folio);
|
||
return false;
|
||
}
|
||
|
||
/* see the comment on MAX_NR_TIERS */
|
||
if (!folio_test_referenced(folio))
|
||
set_mask_bits(&folio->flags, LRU_REFS_MASK | LRU_REFS_FLAGS, 0);
|
||
|
||
/* for shrink_folio_list() */
|
||
folio_clear_reclaim(folio);
|
||
folio_clear_referenced(folio);
|
||
|
||
success = lru_gen_del_folio(lruvec, folio, true);
|
||
VM_WARN_ON_ONCE_FOLIO(!success, folio);
|
||
|
||
return true;
|
||
}
|
||
|
||
static int scan_folios(struct lruvec *lruvec, struct scan_control *sc,
|
||
int type, int tier, struct list_head *list)
|
||
{
|
||
int i;
|
||
int gen;
|
||
enum vm_event_item item;
|
||
int sorted = 0;
|
||
int scanned = 0;
|
||
int isolated = 0;
|
||
int skipped = 0;
|
||
int remaining = MAX_LRU_BATCH;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
|
||
VM_WARN_ON_ONCE(!list_empty(list));
|
||
|
||
if (get_nr_gens(lruvec, type) == MIN_NR_GENS)
|
||
return 0;
|
||
|
||
gen = lru_gen_from_seq(lrugen->min_seq[type]);
|
||
|
||
for (i = MAX_NR_ZONES; i > 0; i--) {
|
||
LIST_HEAD(moved);
|
||
int skipped_zone = 0;
|
||
int zone = (sc->reclaim_idx + i) % MAX_NR_ZONES;
|
||
struct list_head *head = &lrugen->folios[gen][type][zone];
|
||
|
||
while (!list_empty(head)) {
|
||
struct folio *folio = lru_to_folio(head);
|
||
int delta = folio_nr_pages(folio);
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio);
|
||
|
||
scanned += delta;
|
||
|
||
if (sort_folio(lruvec, folio, sc, tier))
|
||
sorted += delta;
|
||
else if (isolate_folio(lruvec, folio, sc)) {
|
||
list_add(&folio->lru, list);
|
||
isolated += delta;
|
||
} else {
|
||
list_move(&folio->lru, &moved);
|
||
skipped_zone += delta;
|
||
}
|
||
|
||
if (!--remaining || max(isolated, skipped_zone) >= MIN_LRU_BATCH)
|
||
break;
|
||
}
|
||
|
||
if (skipped_zone) {
|
||
list_splice(&moved, head);
|
||
__count_zid_vm_events(PGSCAN_SKIP, zone, skipped_zone);
|
||
skipped += skipped_zone;
|
||
}
|
||
|
||
if (!remaining || isolated >= MIN_LRU_BATCH)
|
||
break;
|
||
}
|
||
|
||
item = PGSCAN_KSWAPD + reclaimer_offset();
|
||
if (!cgroup_reclaim(sc)) {
|
||
__count_vm_events(item, isolated);
|
||
__count_vm_events(PGREFILL, sorted);
|
||
}
|
||
__count_memcg_events(memcg, item, isolated);
|
||
__count_memcg_events(memcg, PGREFILL, sorted);
|
||
__count_vm_events(PGSCAN_ANON + type, isolated);
|
||
trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, MAX_LRU_BATCH,
|
||
scanned, skipped, isolated,
|
||
type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON);
|
||
|
||
/*
|
||
* There might not be eligible folios due to reclaim_idx. Check the
|
||
* remaining to prevent livelock if it's not making progress.
|
||
*/
|
||
return isolated || !remaining ? scanned : 0;
|
||
}
|
||
|
||
static int get_tier_idx(struct lruvec *lruvec, int type)
|
||
{
|
||
int tier;
|
||
struct ctrl_pos sp, pv;
|
||
|
||
/*
|
||
* To leave a margin for fluctuations, use a larger gain factor (1:2).
|
||
* This value is chosen because any other tier would have at least twice
|
||
* as many refaults as the first tier.
|
||
*/
|
||
read_ctrl_pos(lruvec, type, 0, 1, &sp);
|
||
for (tier = 1; tier < MAX_NR_TIERS; tier++) {
|
||
read_ctrl_pos(lruvec, type, tier, 2, &pv);
|
||
if (!positive_ctrl_err(&sp, &pv))
|
||
break;
|
||
}
|
||
|
||
return tier - 1;
|
||
}
|
||
|
||
static int get_type_to_scan(struct lruvec *lruvec, int swappiness, int *tier_idx)
|
||
{
|
||
int type, tier;
|
||
struct ctrl_pos sp, pv;
|
||
int gain[ANON_AND_FILE] = { swappiness, MAX_SWAPPINESS - swappiness };
|
||
|
||
/*
|
||
* Compare the first tier of anon with that of file to determine which
|
||
* type to scan. Also need to compare other tiers of the selected type
|
||
* with the first tier of the other type to determine the last tier (of
|
||
* the selected type) to evict.
|
||
*/
|
||
read_ctrl_pos(lruvec, LRU_GEN_ANON, 0, gain[LRU_GEN_ANON], &sp);
|
||
read_ctrl_pos(lruvec, LRU_GEN_FILE, 0, gain[LRU_GEN_FILE], &pv);
|
||
type = positive_ctrl_err(&sp, &pv);
|
||
|
||
read_ctrl_pos(lruvec, !type, 0, gain[!type], &sp);
|
||
for (tier = 1; tier < MAX_NR_TIERS; tier++) {
|
||
read_ctrl_pos(lruvec, type, tier, gain[type], &pv);
|
||
if (!positive_ctrl_err(&sp, &pv))
|
||
break;
|
||
}
|
||
|
||
*tier_idx = tier - 1;
|
||
|
||
return type;
|
||
}
|
||
|
||
static int isolate_folios(struct lruvec *lruvec, struct scan_control *sc, int swappiness,
|
||
int *type_scanned, struct list_head *list)
|
||
{
|
||
int i;
|
||
int type;
|
||
int scanned;
|
||
int tier = -1;
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
/*
|
||
* Try to make the obvious choice first, and if anon and file are both
|
||
* available from the same generation,
|
||
* 1. Interpret swappiness 1 as file first and MAX_SWAPPINESS as anon
|
||
* first.
|
||
* 2. If !__GFP_IO, file first since clean pagecache is more likely to
|
||
* exist than clean swapcache.
|
||
*/
|
||
if (!swappiness)
|
||
type = LRU_GEN_FILE;
|
||
else if (min_seq[LRU_GEN_ANON] < min_seq[LRU_GEN_FILE])
|
||
type = LRU_GEN_ANON;
|
||
else if (swappiness == 1)
|
||
type = LRU_GEN_FILE;
|
||
else if (swappiness == MAX_SWAPPINESS)
|
||
type = LRU_GEN_ANON;
|
||
else if (!(sc->gfp_mask & __GFP_IO))
|
||
type = LRU_GEN_FILE;
|
||
else
|
||
type = get_type_to_scan(lruvec, swappiness, &tier);
|
||
|
||
for (i = !swappiness; i < ANON_AND_FILE; i++) {
|
||
if (tier < 0)
|
||
tier = get_tier_idx(lruvec, type);
|
||
|
||
scanned = scan_folios(lruvec, sc, type, tier, list);
|
||
if (scanned)
|
||
break;
|
||
|
||
type = !type;
|
||
tier = -1;
|
||
}
|
||
|
||
*type_scanned = type;
|
||
|
||
return scanned;
|
||
}
|
||
|
||
static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swappiness)
|
||
{
|
||
int type;
|
||
int scanned;
|
||
int reclaimed;
|
||
LIST_HEAD(list);
|
||
LIST_HEAD(clean);
|
||
struct folio *folio;
|
||
struct folio *next;
|
||
enum vm_event_item item;
|
||
struct reclaim_stat stat;
|
||
struct lru_gen_mm_walk *walk;
|
||
bool skip_retry = false;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
scanned = isolate_folios(lruvec, sc, swappiness, &type, &list);
|
||
|
||
scanned += try_to_inc_min_seq(lruvec, swappiness);
|
||
|
||
if (get_nr_gens(lruvec, !swappiness) == MIN_NR_GENS)
|
||
scanned = 0;
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
if (list_empty(&list))
|
||
return scanned;
|
||
retry:
|
||
reclaimed = shrink_folio_list(&list, pgdat, sc, &stat, false);
|
||
sc->nr_reclaimed += reclaimed;
|
||
trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id,
|
||
scanned, reclaimed, &stat, sc->priority,
|
||
type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON);
|
||
|
||
list_for_each_entry_safe_reverse(folio, next, &list, lru) {
|
||
if (!folio_evictable(folio)) {
|
||
list_del(&folio->lru);
|
||
folio_putback_lru(folio);
|
||
continue;
|
||
}
|
||
|
||
if (folio_test_reclaim(folio) &&
|
||
(folio_test_dirty(folio) || folio_test_writeback(folio))) {
|
||
/* restore LRU_REFS_FLAGS cleared by isolate_folio() */
|
||
if (folio_test_workingset(folio))
|
||
folio_set_referenced(folio);
|
||
continue;
|
||
}
|
||
|
||
if (skip_retry || folio_test_active(folio) || folio_test_referenced(folio) ||
|
||
folio_mapped(folio) || folio_test_locked(folio) ||
|
||
folio_test_dirty(folio) || folio_test_writeback(folio)) {
|
||
/* don't add rejected folios to the oldest generation */
|
||
set_mask_bits(&folio->flags, LRU_REFS_MASK | LRU_REFS_FLAGS,
|
||
BIT(PG_active));
|
||
continue;
|
||
}
|
||
|
||
/* retry folios that may have missed folio_rotate_reclaimable() */
|
||
list_move(&folio->lru, &clean);
|
||
}
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
move_folios_to_lru(lruvec, &list);
|
||
|
||
walk = current->reclaim_state->mm_walk;
|
||
if (walk && walk->batched) {
|
||
walk->lruvec = lruvec;
|
||
reset_batch_size(walk);
|
||
}
|
||
|
||
item = PGSTEAL_KSWAPD + reclaimer_offset();
|
||
if (!cgroup_reclaim(sc))
|
||
__count_vm_events(item, reclaimed);
|
||
__count_memcg_events(memcg, item, reclaimed);
|
||
__count_vm_events(PGSTEAL_ANON + type, reclaimed);
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
list_splice_init(&clean, &list);
|
||
|
||
if (!list_empty(&list)) {
|
||
skip_retry = true;
|
||
goto retry;
|
||
}
|
||
|
||
return scanned;
|
||
}
|
||
|
||
static bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq,
|
||
bool can_swap, unsigned long *nr_to_scan)
|
||
{
|
||
int gen, type, zone;
|
||
unsigned long old = 0;
|
||
unsigned long young = 0;
|
||
unsigned long total = 0;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
/* whether this lruvec is completely out of cold folios */
|
||
if (min_seq[!can_swap] + MIN_NR_GENS > max_seq) {
|
||
*nr_to_scan = 0;
|
||
return true;
|
||
}
|
||
|
||
for (type = !can_swap; type < ANON_AND_FILE; type++) {
|
||
unsigned long seq;
|
||
|
||
for (seq = min_seq[type]; seq <= max_seq; seq++) {
|
||
unsigned long size = 0;
|
||
|
||
gen = lru_gen_from_seq(seq);
|
||
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++)
|
||
size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
|
||
|
||
total += size;
|
||
if (seq == max_seq)
|
||
young += size;
|
||
else if (seq + MIN_NR_GENS == max_seq)
|
||
old += size;
|
||
}
|
||
}
|
||
|
||
*nr_to_scan = total;
|
||
|
||
/*
|
||
* The aging tries to be lazy to reduce the overhead, while the eviction
|
||
* stalls when the number of generations reaches MIN_NR_GENS. Hence, the
|
||
* ideal number of generations is MIN_NR_GENS+1.
|
||
*/
|
||
if (min_seq[!can_swap] + MIN_NR_GENS < max_seq)
|
||
return false;
|
||
|
||
/*
|
||
* It's also ideal to spread pages out evenly, i.e., 1/(MIN_NR_GENS+1)
|
||
* of the total number of pages for each generation. A reasonable range
|
||
* for this average portion is [1/MIN_NR_GENS, 1/(MIN_NR_GENS+2)]. The
|
||
* aging cares about the upper bound of hot pages, while the eviction
|
||
* cares about the lower bound of cold pages.
|
||
*/
|
||
if (young * MIN_NR_GENS > total)
|
||
return true;
|
||
if (old * (MIN_NR_GENS + 2) < total)
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
/*
|
||
* For future optimizations:
|
||
* 1. Defer try_to_inc_max_seq() to workqueues to reduce latency for memcg
|
||
* reclaim.
|
||
*/
|
||
static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, bool can_swap)
|
||
{
|
||
bool success;
|
||
unsigned long nr_to_scan;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
|
||
if (mem_cgroup_below_min(sc->target_mem_cgroup, memcg))
|
||
return -1;
|
||
|
||
success = should_run_aging(lruvec, max_seq, can_swap, &nr_to_scan);
|
||
|
||
/* try to scrape all its memory if this memcg was deleted */
|
||
if (nr_to_scan && !mem_cgroup_online(memcg))
|
||
return nr_to_scan;
|
||
|
||
/* try to get away with not aging at the default priority */
|
||
if (!success || sc->priority == DEF_PRIORITY)
|
||
return nr_to_scan >> sc->priority;
|
||
|
||
/* stop scanning this lruvec as it's low on cold folios */
|
||
return try_to_inc_max_seq(lruvec, max_seq, can_swap, false) ? -1 : 0;
|
||
}
|
||
|
||
static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
int i;
|
||
enum zone_watermarks mark;
|
||
|
||
/* don't abort memcg reclaim to ensure fairness */
|
||
if (!root_reclaim(sc))
|
||
return false;
|
||
|
||
if (sc->nr_reclaimed >= max(sc->nr_to_reclaim, compact_gap(sc->order)))
|
||
return true;
|
||
|
||
/* check the order to exclude compaction-induced reclaim */
|
||
if (!current_is_kswapd() || sc->order)
|
||
return false;
|
||
|
||
mark = sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING ?
|
||
WMARK_PROMO : WMARK_HIGH;
|
||
|
||
for (i = 0; i <= sc->reclaim_idx; i++) {
|
||
struct zone *zone = lruvec_pgdat(lruvec)->node_zones + i;
|
||
unsigned long size = wmark_pages(zone, mark) + MIN_LRU_BATCH;
|
||
|
||
if (managed_zone(zone) && !zone_watermark_ok(zone, 0, size, sc->reclaim_idx, 0))
|
||
return false;
|
||
}
|
||
|
||
/* kswapd should abort if all eligible zones are safe */
|
||
return true;
|
||
}
|
||
|
||
static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
long nr_to_scan;
|
||
unsigned long scanned = 0;
|
||
int swappiness = get_swappiness(lruvec, sc);
|
||
|
||
while (true) {
|
||
int delta;
|
||
|
||
nr_to_scan = get_nr_to_scan(lruvec, sc, swappiness);
|
||
if (nr_to_scan <= 0)
|
||
break;
|
||
|
||
delta = evict_folios(lruvec, sc, swappiness);
|
||
if (!delta)
|
||
break;
|
||
|
||
scanned += delta;
|
||
if (scanned >= nr_to_scan)
|
||
break;
|
||
|
||
if (should_abort_scan(lruvec, sc))
|
||
break;
|
||
|
||
cond_resched();
|
||
}
|
||
|
||
/* whether this lruvec should be rotated */
|
||
return nr_to_scan < 0;
|
||
}
|
||
|
||
static int shrink_one(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
bool success;
|
||
unsigned long scanned = sc->nr_scanned;
|
||
unsigned long reclaimed = sc->nr_reclaimed;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
|
||
/* lru_gen_age_node() called mem_cgroup_calculate_protection() */
|
||
if (mem_cgroup_below_min(NULL, memcg))
|
||
return MEMCG_LRU_YOUNG;
|
||
|
||
if (mem_cgroup_below_low(NULL, memcg)) {
|
||
/* see the comment on MEMCG_NR_GENS */
|
||
if (READ_ONCE(lruvec->lrugen.seg) != MEMCG_LRU_TAIL)
|
||
return MEMCG_LRU_TAIL;
|
||
|
||
memcg_memory_event(memcg, MEMCG_LOW);
|
||
}
|
||
|
||
success = try_to_shrink_lruvec(lruvec, sc);
|
||
|
||
shrink_slab(sc->gfp_mask, pgdat->node_id, memcg, sc->priority);
|
||
|
||
if (!sc->proactive)
|
||
vmpressure(sc->gfp_mask, memcg, false, sc->nr_scanned - scanned,
|
||
sc->nr_reclaimed - reclaimed);
|
||
|
||
flush_reclaim_state(sc);
|
||
|
||
if (success && mem_cgroup_online(memcg))
|
||
return MEMCG_LRU_YOUNG;
|
||
|
||
if (!success && lruvec_is_sizable(lruvec, sc))
|
||
return 0;
|
||
|
||
/* one retry if offlined or too small */
|
||
return READ_ONCE(lruvec->lrugen.seg) != MEMCG_LRU_TAIL ?
|
||
MEMCG_LRU_TAIL : MEMCG_LRU_YOUNG;
|
||
}
|
||
|
||
static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
int op;
|
||
int gen;
|
||
int bin;
|
||
int first_bin;
|
||
struct lruvec *lruvec;
|
||
struct lru_gen_folio *lrugen;
|
||
struct mem_cgroup *memcg;
|
||
struct hlist_nulls_node *pos;
|
||
|
||
gen = get_memcg_gen(READ_ONCE(pgdat->memcg_lru.seq));
|
||
bin = first_bin = get_random_u32_below(MEMCG_NR_BINS);
|
||
restart:
|
||
op = 0;
|
||
memcg = NULL;
|
||
|
||
rcu_read_lock();
|
||
|
||
hlist_nulls_for_each_entry_rcu(lrugen, pos, &pgdat->memcg_lru.fifo[gen][bin], list) {
|
||
if (op) {
|
||
lru_gen_rotate_memcg(lruvec, op);
|
||
op = 0;
|
||
}
|
||
|
||
mem_cgroup_put(memcg);
|
||
memcg = NULL;
|
||
|
||
if (gen != READ_ONCE(lrugen->gen))
|
||
continue;
|
||
|
||
lruvec = container_of(lrugen, struct lruvec, lrugen);
|
||
memcg = lruvec_memcg(lruvec);
|
||
|
||
if (!mem_cgroup_tryget(memcg)) {
|
||
lru_gen_release_memcg(memcg);
|
||
memcg = NULL;
|
||
continue;
|
||
}
|
||
|
||
rcu_read_unlock();
|
||
|
||
op = shrink_one(lruvec, sc);
|
||
|
||
rcu_read_lock();
|
||
|
||
if (should_abort_scan(lruvec, sc))
|
||
break;
|
||
}
|
||
|
||
rcu_read_unlock();
|
||
|
||
if (op)
|
||
lru_gen_rotate_memcg(lruvec, op);
|
||
|
||
mem_cgroup_put(memcg);
|
||
|
||
if (!is_a_nulls(pos))
|
||
return;
|
||
|
||
/* restart if raced with lru_gen_rotate_memcg() */
|
||
if (gen != get_nulls_value(pos))
|
||
goto restart;
|
||
|
||
/* try the rest of the bins of the current generation */
|
||
bin = get_memcg_bin(bin + 1);
|
||
if (bin != first_bin)
|
||
goto restart;
|
||
}
|
||
|
||
static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
struct blk_plug plug;
|
||
|
||
VM_WARN_ON_ONCE(root_reclaim(sc));
|
||
VM_WARN_ON_ONCE(!sc->may_writepage || !sc->may_unmap);
|
||
|
||
lru_add_drain();
|
||
|
||
blk_start_plug(&plug);
|
||
|
||
set_mm_walk(NULL, sc->proactive);
|
||
|
||
if (try_to_shrink_lruvec(lruvec, sc))
|
||
lru_gen_rotate_memcg(lruvec, MEMCG_LRU_YOUNG);
|
||
|
||
clear_mm_walk();
|
||
|
||
blk_finish_plug(&plug);
|
||
}
|
||
|
||
static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
struct blk_plug plug;
|
||
unsigned long reclaimed = sc->nr_reclaimed;
|
||
|
||
VM_WARN_ON_ONCE(!root_reclaim(sc));
|
||
|
||
/*
|
||
* Unmapped clean folios are already prioritized. Scanning for more of
|
||
* them is likely futile and can cause high reclaim latency when there
|
||
* is a large number of memcgs.
|
||
*/
|
||
if (!sc->may_writepage || !sc->may_unmap)
|
||
goto done;
|
||
|
||
lru_add_drain();
|
||
|
||
blk_start_plug(&plug);
|
||
|
||
set_mm_walk(pgdat, sc->proactive);
|
||
|
||
set_initial_priority(pgdat, sc);
|
||
|
||
if (current_is_kswapd())
|
||
sc->nr_reclaimed = 0;
|
||
|
||
if (mem_cgroup_disabled())
|
||
shrink_one(&pgdat->__lruvec, sc);
|
||
else
|
||
shrink_many(pgdat, sc);
|
||
|
||
if (current_is_kswapd())
|
||
sc->nr_reclaimed += reclaimed;
|
||
|
||
clear_mm_walk();
|
||
|
||
blk_finish_plug(&plug);
|
||
done:
|
||
if (sc->nr_reclaimed > reclaimed)
|
||
pgdat->kswapd_failures = 0;
|
||
}
|
||
|
||
/******************************************************************************
|
||
* state change
|
||
******************************************************************************/
|
||
|
||
static bool __maybe_unused state_is_valid(struct lruvec *lruvec)
|
||
{
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
|
||
if (lrugen->enabled) {
|
||
enum lru_list lru;
|
||
|
||
for_each_evictable_lru(lru) {
|
||
if (!list_empty(&lruvec->lists[lru]))
|
||
return false;
|
||
}
|
||
} else {
|
||
int gen, type, zone;
|
||
|
||
for_each_gen_type_zone(gen, type, zone) {
|
||
if (!list_empty(&lrugen->folios[gen][type][zone]))
|
||
return false;
|
||
}
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
static bool fill_evictable(struct lruvec *lruvec)
|
||
{
|
||
enum lru_list lru;
|
||
int remaining = MAX_LRU_BATCH;
|
||
|
||
for_each_evictable_lru(lru) {
|
||
int type = is_file_lru(lru);
|
||
bool active = is_active_lru(lru);
|
||
struct list_head *head = &lruvec->lists[lru];
|
||
|
||
while (!list_empty(head)) {
|
||
bool success;
|
||
struct folio *folio = lru_to_folio(head);
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio) != active, folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_lru_gen(folio) != -1, folio);
|
||
|
||
lruvec_del_folio(lruvec, folio);
|
||
success = lru_gen_add_folio(lruvec, folio, false);
|
||
VM_WARN_ON_ONCE(!success);
|
||
|
||
if (!--remaining)
|
||
return false;
|
||
}
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
static bool drain_evictable(struct lruvec *lruvec)
|
||
{
|
||
int gen, type, zone;
|
||
int remaining = MAX_LRU_BATCH;
|
||
|
||
for_each_gen_type_zone(gen, type, zone) {
|
||
struct list_head *head = &lruvec->lrugen.folios[gen][type][zone];
|
||
|
||
while (!list_empty(head)) {
|
||
bool success;
|
||
struct folio *folio = lru_to_folio(head);
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio);
|
||
|
||
success = lru_gen_del_folio(lruvec, folio, false);
|
||
VM_WARN_ON_ONCE(!success);
|
||
lruvec_add_folio(lruvec, folio);
|
||
|
||
if (!--remaining)
|
||
return false;
|
||
}
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
static void lru_gen_change_state(bool enabled)
|
||
{
|
||
static DEFINE_MUTEX(state_mutex);
|
||
|
||
struct mem_cgroup *memcg;
|
||
|
||
cgroup_lock();
|
||
cpus_read_lock();
|
||
get_online_mems();
|
||
mutex_lock(&state_mutex);
|
||
|
||
if (enabled == lru_gen_enabled())
|
||
goto unlock;
|
||
|
||
if (enabled)
|
||
static_branch_enable_cpuslocked(&lru_gen_caps[LRU_GEN_CORE]);
|
||
else
|
||
static_branch_disable_cpuslocked(&lru_gen_caps[LRU_GEN_CORE]);
|
||
|
||
memcg = mem_cgroup_iter(NULL, NULL, NULL);
|
||
do {
|
||
int nid;
|
||
|
||
for_each_node(nid) {
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
|
||
VM_WARN_ON_ONCE(!state_is_valid(lruvec));
|
||
|
||
lruvec->lrugen.enabled = enabled;
|
||
|
||
while (!(enabled ? fill_evictable(lruvec) : drain_evictable(lruvec))) {
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
cond_resched();
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
}
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
}
|
||
|
||
cond_resched();
|
||
} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)));
|
||
unlock:
|
||
mutex_unlock(&state_mutex);
|
||
put_online_mems();
|
||
cpus_read_unlock();
|
||
cgroup_unlock();
|
||
}
|
||
|
||
/******************************************************************************
|
||
* sysfs interface
|
||
******************************************************************************/
|
||
|
||
static ssize_t min_ttl_ms_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
|
||
{
|
||
return sysfs_emit(buf, "%u\n", jiffies_to_msecs(READ_ONCE(lru_gen_min_ttl)));
|
||
}
|
||
|
||
/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
|
||
static ssize_t min_ttl_ms_store(struct kobject *kobj, struct kobj_attribute *attr,
|
||
const char *buf, size_t len)
|
||
{
|
||
unsigned int msecs;
|
||
|
||
if (kstrtouint(buf, 0, &msecs))
|
||
return -EINVAL;
|
||
|
||
WRITE_ONCE(lru_gen_min_ttl, msecs_to_jiffies(msecs));
|
||
|
||
return len;
|
||
}
|
||
|
||
static struct kobj_attribute lru_gen_min_ttl_attr = __ATTR_RW(min_ttl_ms);
|
||
|
||
static ssize_t enabled_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
|
||
{
|
||
unsigned int caps = 0;
|
||
|
||
if (get_cap(LRU_GEN_CORE))
|
||
caps |= BIT(LRU_GEN_CORE);
|
||
|
||
if (should_walk_mmu())
|
||
caps |= BIT(LRU_GEN_MM_WALK);
|
||
|
||
if (should_clear_pmd_young())
|
||
caps |= BIT(LRU_GEN_NONLEAF_YOUNG);
|
||
|
||
return sysfs_emit(buf, "0x%04x\n", caps);
|
||
}
|
||
|
||
/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
|
||
static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
|
||
const char *buf, size_t len)
|
||
{
|
||
int i;
|
||
unsigned int caps;
|
||
|
||
if (tolower(*buf) == 'n')
|
||
caps = 0;
|
||
else if (tolower(*buf) == 'y')
|
||
caps = -1;
|
||
else if (kstrtouint(buf, 0, &caps))
|
||
return -EINVAL;
|
||
|
||
for (i = 0; i < NR_LRU_GEN_CAPS; i++) {
|
||
bool enabled = caps & BIT(i);
|
||
|
||
if (i == LRU_GEN_CORE)
|
||
lru_gen_change_state(enabled);
|
||
else if (enabled)
|
||
static_branch_enable(&lru_gen_caps[i]);
|
||
else
|
||
static_branch_disable(&lru_gen_caps[i]);
|
||
}
|
||
|
||
return len;
|
||
}
|
||
|
||
static struct kobj_attribute lru_gen_enabled_attr = __ATTR_RW(enabled);
|
||
|
||
static struct attribute *lru_gen_attrs[] = {
|
||
&lru_gen_min_ttl_attr.attr,
|
||
&lru_gen_enabled_attr.attr,
|
||
NULL
|
||
};
|
||
|
||
static const struct attribute_group lru_gen_attr_group = {
|
||
.name = "lru_gen",
|
||
.attrs = lru_gen_attrs,
|
||
};
|
||
|
||
/******************************************************************************
|
||
* debugfs interface
|
||
******************************************************************************/
|
||
|
||
static void *lru_gen_seq_start(struct seq_file *m, loff_t *pos)
|
||
{
|
||
struct mem_cgroup *memcg;
|
||
loff_t nr_to_skip = *pos;
|
||
|
||
m->private = kvmalloc(PATH_MAX, GFP_KERNEL);
|
||
if (!m->private)
|
||
return ERR_PTR(-ENOMEM);
|
||
|
||
memcg = mem_cgroup_iter(NULL, NULL, NULL);
|
||
do {
|
||
int nid;
|
||
|
||
for_each_node_state(nid, N_MEMORY) {
|
||
if (!nr_to_skip--)
|
||
return get_lruvec(memcg, nid);
|
||
}
|
||
} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)));
|
||
|
||
return NULL;
|
||
}
|
||
|
||
static void lru_gen_seq_stop(struct seq_file *m, void *v)
|
||
{
|
||
if (!IS_ERR_OR_NULL(v))
|
||
mem_cgroup_iter_break(NULL, lruvec_memcg(v));
|
||
|
||
kvfree(m->private);
|
||
m->private = NULL;
|
||
}
|
||
|
||
static void *lru_gen_seq_next(struct seq_file *m, void *v, loff_t *pos)
|
||
{
|
||
int nid = lruvec_pgdat(v)->node_id;
|
||
struct mem_cgroup *memcg = lruvec_memcg(v);
|
||
|
||
++*pos;
|
||
|
||
nid = next_memory_node(nid);
|
||
if (nid == MAX_NUMNODES) {
|
||
memcg = mem_cgroup_iter(NULL, memcg, NULL);
|
||
if (!memcg)
|
||
return NULL;
|
||
|
||
nid = first_memory_node;
|
||
}
|
||
|
||
return get_lruvec(memcg, nid);
|
||
}
|
||
|
||
static void lru_gen_seq_show_full(struct seq_file *m, struct lruvec *lruvec,
|
||
unsigned long max_seq, unsigned long *min_seq,
|
||
unsigned long seq)
|
||
{
|
||
int i;
|
||
int type, tier;
|
||
int hist = lru_hist_from_seq(seq);
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
for (tier = 0; tier < MAX_NR_TIERS; tier++) {
|
||
seq_printf(m, " %10d", tier);
|
||
for (type = 0; type < ANON_AND_FILE; type++) {
|
||
const char *s = "xxx";
|
||
unsigned long n[3] = {};
|
||
|
||
if (seq == max_seq) {
|
||
s = "RTx";
|
||
n[0] = READ_ONCE(lrugen->avg_refaulted[type][tier]);
|
||
n[1] = READ_ONCE(lrugen->avg_total[type][tier]);
|
||
} else if (seq == min_seq[type] || NR_HIST_GENS > 1) {
|
||
s = "rep";
|
||
n[0] = atomic_long_read(&lrugen->refaulted[hist][type][tier]);
|
||
n[1] = atomic_long_read(&lrugen->evicted[hist][type][tier]);
|
||
if (tier)
|
||
n[2] = READ_ONCE(lrugen->protected[hist][type][tier - 1]);
|
||
}
|
||
|
||
for (i = 0; i < 3; i++)
|
||
seq_printf(m, " %10lu%c", n[i], s[i]);
|
||
}
|
||
seq_putc(m, '\n');
|
||
}
|
||
|
||
if (!mm_state)
|
||
return;
|
||
|
||
seq_puts(m, " ");
|
||
for (i = 0; i < NR_MM_STATS; i++) {
|
||
const char *s = "xxxx";
|
||
unsigned long n = 0;
|
||
|
||
if (seq == max_seq && NR_HIST_GENS == 1) {
|
||
s = "TYFA";
|
||
n = READ_ONCE(mm_state->stats[hist][i]);
|
||
} else if (seq != max_seq && NR_HIST_GENS > 1) {
|
||
s = "tyfa";
|
||
n = READ_ONCE(mm_state->stats[hist][i]);
|
||
}
|
||
|
||
seq_printf(m, " %10lu%c", n, s[i]);
|
||
}
|
||
seq_putc(m, '\n');
|
||
}
|
||
|
||
/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
|
||
static int lru_gen_seq_show(struct seq_file *m, void *v)
|
||
{
|
||
unsigned long seq;
|
||
bool full = !debugfs_real_fops(m->file)->write;
|
||
struct lruvec *lruvec = v;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
int nid = lruvec_pgdat(lruvec)->node_id;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
if (nid == first_memory_node) {
|
||
const char *path = memcg ? m->private : "";
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
if (memcg)
|
||
cgroup_path(memcg->css.cgroup, m->private, PATH_MAX);
|
||
#endif
|
||
seq_printf(m, "memcg %5hu %s\n", mem_cgroup_id(memcg), path);
|
||
}
|
||
|
||
seq_printf(m, " node %5d\n", nid);
|
||
|
||
if (!full)
|
||
seq = min_seq[LRU_GEN_ANON];
|
||
else if (max_seq >= MAX_NR_GENS)
|
||
seq = max_seq - MAX_NR_GENS + 1;
|
||
else
|
||
seq = 0;
|
||
|
||
for (; seq <= max_seq; seq++) {
|
||
int type, zone;
|
||
int gen = lru_gen_from_seq(seq);
|
||
unsigned long birth = READ_ONCE(lruvec->lrugen.timestamps[gen]);
|
||
|
||
seq_printf(m, " %10lu %10u", seq, jiffies_to_msecs(jiffies - birth));
|
||
|
||
for (type = 0; type < ANON_AND_FILE; type++) {
|
||
unsigned long size = 0;
|
||
char mark = full && seq < min_seq[type] ? 'x' : ' ';
|
||
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++)
|
||
size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
|
||
|
||
seq_printf(m, " %10lu%c", size, mark);
|
||
}
|
||
|
||
seq_putc(m, '\n');
|
||
|
||
if (full)
|
||
lru_gen_seq_show_full(m, lruvec, max_seq, min_seq, seq);
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
static const struct seq_operations lru_gen_seq_ops = {
|
||
.start = lru_gen_seq_start,
|
||
.stop = lru_gen_seq_stop,
|
||
.next = lru_gen_seq_next,
|
||
.show = lru_gen_seq_show,
|
||
};
|
||
|
||
static int run_aging(struct lruvec *lruvec, unsigned long seq,
|
||
bool can_swap, bool force_scan)
|
||
{
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
if (seq < max_seq)
|
||
return 0;
|
||
|
||
if (seq > max_seq)
|
||
return -EINVAL;
|
||
|
||
if (!force_scan && min_seq[!can_swap] + MAX_NR_GENS - 1 <= max_seq)
|
||
return -ERANGE;
|
||
|
||
try_to_inc_max_seq(lruvec, max_seq, can_swap, force_scan);
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int run_eviction(struct lruvec *lruvec, unsigned long seq, struct scan_control *sc,
|
||
int swappiness, unsigned long nr_to_reclaim)
|
||
{
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
|
||
if (seq + MIN_NR_GENS > max_seq)
|
||
return -EINVAL;
|
||
|
||
sc->nr_reclaimed = 0;
|
||
|
||
while (!signal_pending(current)) {
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
if (seq < min_seq[!swappiness])
|
||
return 0;
|
||
|
||
if (sc->nr_reclaimed >= nr_to_reclaim)
|
||
return 0;
|
||
|
||
if (!evict_folios(lruvec, sc, swappiness))
|
||
return 0;
|
||
|
||
cond_resched();
|
||
}
|
||
|
||
return -EINTR;
|
||
}
|
||
|
||
static int run_cmd(char cmd, int memcg_id, int nid, unsigned long seq,
|
||
struct scan_control *sc, int swappiness, unsigned long opt)
|
||
{
|
||
struct lruvec *lruvec;
|
||
int err = -EINVAL;
|
||
struct mem_cgroup *memcg = NULL;
|
||
|
||
if (nid < 0 || nid >= MAX_NUMNODES || !node_state(nid, N_MEMORY))
|
||
return -EINVAL;
|
||
|
||
if (!mem_cgroup_disabled()) {
|
||
rcu_read_lock();
|
||
|
||
memcg = mem_cgroup_from_id(memcg_id);
|
||
if (!mem_cgroup_tryget(memcg))
|
||
memcg = NULL;
|
||
|
||
rcu_read_unlock();
|
||
|
||
if (!memcg)
|
||
return -EINVAL;
|
||
}
|
||
|
||
if (memcg_id != mem_cgroup_id(memcg))
|
||
goto done;
|
||
|
||
lruvec = get_lruvec(memcg, nid);
|
||
|
||
if (swappiness < MIN_SWAPPINESS)
|
||
swappiness = get_swappiness(lruvec, sc);
|
||
else if (swappiness > MAX_SWAPPINESS)
|
||
goto done;
|
||
|
||
switch (cmd) {
|
||
case '+':
|
||
err = run_aging(lruvec, seq, swappiness, opt);
|
||
break;
|
||
case '-':
|
||
err = run_eviction(lruvec, seq, sc, swappiness, opt);
|
||
break;
|
||
}
|
||
done:
|
||
mem_cgroup_put(memcg);
|
||
|
||
return err;
|
||
}
|
||
|
||
/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
|
||
static ssize_t lru_gen_seq_write(struct file *file, const char __user *src,
|
||
size_t len, loff_t *pos)
|
||
{
|
||
void *buf;
|
||
char *cur, *next;
|
||
unsigned int flags;
|
||
struct blk_plug plug;
|
||
int err = -EINVAL;
|
||
struct scan_control sc = {
|
||
.may_writepage = true,
|
||
.may_unmap = true,
|
||
.may_swap = true,
|
||
.reclaim_idx = MAX_NR_ZONES - 1,
|
||
.gfp_mask = GFP_KERNEL,
|
||
};
|
||
|
||
buf = kvmalloc(len + 1, GFP_KERNEL);
|
||
if (!buf)
|
||
return -ENOMEM;
|
||
|
||
if (copy_from_user(buf, src, len)) {
|
||
kvfree(buf);
|
||
return -EFAULT;
|
||
}
|
||
|
||
set_task_reclaim_state(current, &sc.reclaim_state);
|
||
flags = memalloc_noreclaim_save();
|
||
blk_start_plug(&plug);
|
||
if (!set_mm_walk(NULL, true)) {
|
||
err = -ENOMEM;
|
||
goto done;
|
||
}
|
||
|
||
next = buf;
|
||
next[len] = '\0';
|
||
|
||
while ((cur = strsep(&next, ",;\n"))) {
|
||
int n;
|
||
int end;
|
||
char cmd;
|
||
unsigned int memcg_id;
|
||
unsigned int nid;
|
||
unsigned long seq;
|
||
unsigned int swappiness = -1;
|
||
unsigned long opt = -1;
|
||
|
||
cur = skip_spaces(cur);
|
||
if (!*cur)
|
||
continue;
|
||
|
||
n = sscanf(cur, "%c %u %u %lu %n %u %n %lu %n", &cmd, &memcg_id, &nid,
|
||
&seq, &end, &swappiness, &end, &opt, &end);
|
||
if (n < 4 || cur[end]) {
|
||
err = -EINVAL;
|
||
break;
|
||
}
|
||
|
||
err = run_cmd(cmd, memcg_id, nid, seq, &sc, swappiness, opt);
|
||
if (err)
|
||
break;
|
||
}
|
||
done:
|
||
clear_mm_walk();
|
||
blk_finish_plug(&plug);
|
||
memalloc_noreclaim_restore(flags);
|
||
set_task_reclaim_state(current, NULL);
|
||
|
||
kvfree(buf);
|
||
|
||
return err ? : len;
|
||
}
|
||
|
||
static int lru_gen_seq_open(struct inode *inode, struct file *file)
|
||
{
|
||
return seq_open(file, &lru_gen_seq_ops);
|
||
}
|
||
|
||
static const struct file_operations lru_gen_rw_fops = {
|
||
.open = lru_gen_seq_open,
|
||
.read = seq_read,
|
||
.write = lru_gen_seq_write,
|
||
.llseek = seq_lseek,
|
||
.release = seq_release,
|
||
};
|
||
|
||
static const struct file_operations lru_gen_ro_fops = {
|
||
.open = lru_gen_seq_open,
|
||
.read = seq_read,
|
||
.llseek = seq_lseek,
|
||
.release = seq_release,
|
||
};
|
||
|
||
/******************************************************************************
|
||
* initialization
|
||
******************************************************************************/
|
||
|
||
void lru_gen_init_pgdat(struct pglist_data *pgdat)
|
||
{
|
||
int i, j;
|
||
|
||
spin_lock_init(&pgdat->memcg_lru.lock);
|
||
|
||
for (i = 0; i < MEMCG_NR_GENS; i++) {
|
||
for (j = 0; j < MEMCG_NR_BINS; j++)
|
||
INIT_HLIST_NULLS_HEAD(&pgdat->memcg_lru.fifo[i][j], i);
|
||
}
|
||
}
|
||
|
||
void lru_gen_init_lruvec(struct lruvec *lruvec)
|
||
{
|
||
int i;
|
||
int gen, type, zone;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
lrugen->max_seq = MIN_NR_GENS + 1;
|
||
lrugen->enabled = lru_gen_enabled();
|
||
|
||
for (i = 0; i <= MIN_NR_GENS + 1; i++)
|
||
lrugen->timestamps[i] = jiffies;
|
||
|
||
for_each_gen_type_zone(gen, type, zone)
|
||
INIT_LIST_HEAD(&lrugen->folios[gen][type][zone]);
|
||
|
||
if (mm_state)
|
||
mm_state->seq = MIN_NR_GENS;
|
||
}
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
|
||
void lru_gen_init_memcg(struct mem_cgroup *memcg)
|
||
{
|
||
struct lru_gen_mm_list *mm_list = get_mm_list(memcg);
|
||
|
||
if (!mm_list)
|
||
return;
|
||
|
||
INIT_LIST_HEAD(&mm_list->fifo);
|
||
spin_lock_init(&mm_list->lock);
|
||
}
|
||
|
||
void lru_gen_exit_memcg(struct mem_cgroup *memcg)
|
||
{
|
||
int i;
|
||
int nid;
|
||
struct lru_gen_mm_list *mm_list = get_mm_list(memcg);
|
||
|
||
VM_WARN_ON_ONCE(mm_list && !list_empty(&mm_list->fifo));
|
||
|
||
for_each_node(nid) {
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,
|
||
sizeof(lruvec->lrugen.nr_pages)));
|
||
|
||
lruvec->lrugen.list.next = LIST_POISON1;
|
||
|
||
if (!mm_state)
|
||
continue;
|
||
|
||
for (i = 0; i < NR_BLOOM_FILTERS; i++) {
|
||
bitmap_free(mm_state->filters[i]);
|
||
mm_state->filters[i] = NULL;
|
||
}
|
||
}
|
||
}
|
||
|
||
#endif /* CONFIG_MEMCG */
|
||
|
||
static int __init init_lru_gen(void)
|
||
{
|
||
BUILD_BUG_ON(MIN_NR_GENS + 1 >= MAX_NR_GENS);
|
||
BUILD_BUG_ON(BIT(LRU_GEN_WIDTH) <= MAX_NR_GENS);
|
||
|
||
if (sysfs_create_group(mm_kobj, &lru_gen_attr_group))
|
||
pr_err("lru_gen: failed to create sysfs group\n");
|
||
|
||
debugfs_create_file("lru_gen", 0644, NULL, NULL, &lru_gen_rw_fops);
|
||
debugfs_create_file("lru_gen_full", 0444, NULL, NULL, &lru_gen_ro_fops);
|
||
|
||
return 0;
|
||
};
|
||
late_initcall(init_lru_gen);
|
||
|
||
#else /* !CONFIG_LRU_GEN */
|
||
|
||
static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
BUILD_BUG();
|
||
}
|
||
|
||
static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
BUILD_BUG();
|
||
}
|
||
|
||
static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
BUILD_BUG();
|
||
}
|
||
|
||
#endif /* CONFIG_LRU_GEN */
|
||
|
||
static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
unsigned long nr[NR_LRU_LISTS];
|
||
unsigned long targets[NR_LRU_LISTS];
|
||
unsigned long nr_to_scan;
|
||
enum lru_list lru;
|
||
unsigned long nr_reclaimed = 0;
|
||
unsigned long nr_to_reclaim = sc->nr_to_reclaim;
|
||
bool proportional_reclaim;
|
||
struct blk_plug plug;
|
||
|
||
if (lru_gen_enabled() && !root_reclaim(sc)) {
|
||
lru_gen_shrink_lruvec(lruvec, sc);
|
||
return;
|
||
}
|
||
|
||
get_scan_count(lruvec, sc, nr);
|
||
|
||
/* Record the original scan target for proportional adjustments later */
|
||
memcpy(targets, nr, sizeof(nr));
|
||
|
||
/*
|
||
* Global reclaiming within direct reclaim at DEF_PRIORITY is a normal
|
||
* event that can occur when there is little memory pressure e.g.
|
||
* multiple streaming readers/writers. Hence, we do not abort scanning
|
||
* when the requested number of pages are reclaimed when scanning at
|
||
* DEF_PRIORITY on the assumption that the fact we are direct
|
||
* reclaiming implies that kswapd is not keeping up and it is best to
|
||
* do a batch of work at once. For memcg reclaim one check is made to
|
||
* abort proportional reclaim if either the file or anon lru has already
|
||
* dropped to zero at the first pass.
|
||
*/
|
||
proportional_reclaim = (!cgroup_reclaim(sc) && !current_is_kswapd() &&
|
||
sc->priority == DEF_PRIORITY);
|
||
|
||
blk_start_plug(&plug);
|
||
while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
|
||
nr[LRU_INACTIVE_FILE]) {
|
||
unsigned long nr_anon, nr_file, percentage;
|
||
unsigned long nr_scanned;
|
||
|
||
for_each_evictable_lru(lru) {
|
||
if (nr[lru]) {
|
||
nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX);
|
||
nr[lru] -= nr_to_scan;
|
||
|
||
nr_reclaimed += shrink_list(lru, nr_to_scan,
|
||
lruvec, sc);
|
||
}
|
||
}
|
||
|
||
cond_resched();
|
||
|
||
if (nr_reclaimed < nr_to_reclaim || proportional_reclaim)
|
||
continue;
|
||
|
||
/*
|
||
* For kswapd and memcg, reclaim at least the number of pages
|
||
* requested. Ensure that the anon and file LRUs are scanned
|
||
* proportionally what was requested by get_scan_count(). We
|
||
* stop reclaiming one LRU and reduce the amount scanning
|
||
* proportional to the original scan target.
|
||
*/
|
||
nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE];
|
||
nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON];
|
||
|
||
/*
|
||
* It's just vindictive to attack the larger once the smaller
|
||
* has gone to zero. And given the way we stop scanning the
|
||
* smaller below, this makes sure that we only make one nudge
|
||
* towards proportionality once we've got nr_to_reclaim.
|
||
*/
|
||
if (!nr_file || !nr_anon)
|
||
break;
|
||
|
||
if (nr_file > nr_anon) {
|
||
unsigned long scan_target = targets[LRU_INACTIVE_ANON] +
|
||
targets[LRU_ACTIVE_ANON] + 1;
|
||
lru = LRU_BASE;
|
||
percentage = nr_anon * 100 / scan_target;
|
||
} else {
|
||
unsigned long scan_target = targets[LRU_INACTIVE_FILE] +
|
||
targets[LRU_ACTIVE_FILE] + 1;
|
||
lru = LRU_FILE;
|
||
percentage = nr_file * 100 / scan_target;
|
||
}
|
||
|
||
/* Stop scanning the smaller of the LRU */
|
||
nr[lru] = 0;
|
||
nr[lru + LRU_ACTIVE] = 0;
|
||
|
||
/*
|
||
* Recalculate the other LRU scan count based on its original
|
||
* scan target and the percentage scanning already complete
|
||
*/
|
||
lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE;
|
||
nr_scanned = targets[lru] - nr[lru];
|
||
nr[lru] = targets[lru] * (100 - percentage) / 100;
|
||
nr[lru] -= min(nr[lru], nr_scanned);
|
||
|
||
lru += LRU_ACTIVE;
|
||
nr_scanned = targets[lru] - nr[lru];
|
||
nr[lru] = targets[lru] * (100 - percentage) / 100;
|
||
nr[lru] -= min(nr[lru], nr_scanned);
|
||
}
|
||
blk_finish_plug(&plug);
|
||
sc->nr_reclaimed += nr_reclaimed;
|
||
|
||
/*
|
||
* Even if we did not try to evict anon pages at all, we want to
|
||
* rebalance the anon lru active/inactive ratio.
|
||
*/
|
||
if (can_age_anon_pages(lruvec_pgdat(lruvec), sc) &&
|
||
inactive_is_low(lruvec, LRU_INACTIVE_ANON))
|
||
shrink_active_list(SWAP_CLUSTER_MAX, lruvec,
|
||
sc, LRU_ACTIVE_ANON);
|
||
}
|
||
|
||
/* Use reclaim/compaction for costly allocs or under memory pressure */
|
||
static bool in_reclaim_compaction(struct scan_control *sc)
|
||
{
|
||
if (gfp_compaction_allowed(sc->gfp_mask) && sc->order &&
|
||
(sc->order > PAGE_ALLOC_COSTLY_ORDER ||
|
||
sc->priority < DEF_PRIORITY - 2))
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
/*
|
||
* Reclaim/compaction is used for high-order allocation requests. It reclaims
|
||
* order-0 pages before compacting the zone. should_continue_reclaim() returns
|
||
* true if more pages should be reclaimed such that when the page allocator
|
||
* calls try_to_compact_pages() that it will have enough free pages to succeed.
|
||
* It will give up earlier than that if there is difficulty reclaiming pages.
|
||
*/
|
||
static inline bool should_continue_reclaim(struct pglist_data *pgdat,
|
||
unsigned long nr_reclaimed,
|
||
struct scan_control *sc)
|
||
{
|
||
unsigned long pages_for_compaction;
|
||
unsigned long inactive_lru_pages;
|
||
int z;
|
||
|
||
/* If not in reclaim/compaction mode, stop */
|
||
if (!in_reclaim_compaction(sc))
|
||
return false;
|
||
|
||
/*
|
||
* Stop if we failed to reclaim any pages from the last SWAP_CLUSTER_MAX
|
||
* number of pages that were scanned. This will return to the caller
|
||
* with the risk reclaim/compaction and the resulting allocation attempt
|
||
* fails. In the past we have tried harder for __GFP_RETRY_MAYFAIL
|
||
* allocations through requiring that the full LRU list has been scanned
|
||
* first, by assuming that zero delta of sc->nr_scanned means full LRU
|
||
* scan, but that approximation was wrong, and there were corner cases
|
||
* where always a non-zero amount of pages were scanned.
|
||
*/
|
||
if (!nr_reclaimed)
|
||
return false;
|
||
|
||
/* If compaction would go ahead or the allocation would succeed, stop */
|
||
for (z = 0; z <= sc->reclaim_idx; z++) {
|
||
struct zone *zone = &pgdat->node_zones[z];
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
/* Allocation can already succeed, nothing to do */
|
||
if (zone_watermark_ok(zone, sc->order, min_wmark_pages(zone),
|
||
sc->reclaim_idx, 0))
|
||
return false;
|
||
|
||
if (compaction_suitable(zone, sc->order, sc->reclaim_idx))
|
||
return false;
|
||
}
|
||
|
||
/*
|
||
* If we have not reclaimed enough pages for compaction and the
|
||
* inactive lists are large enough, continue reclaiming
|
||
*/
|
||
pages_for_compaction = compact_gap(sc->order);
|
||
inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE);
|
||
if (can_reclaim_anon_pages(NULL, pgdat->node_id, sc))
|
||
inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON);
|
||
|
||
return inactive_lru_pages > pages_for_compaction;
|
||
}
|
||
|
||
static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
|
||
{
|
||
struct mem_cgroup *target_memcg = sc->target_mem_cgroup;
|
||
struct mem_cgroup_reclaim_cookie reclaim = {
|
||
.pgdat = pgdat,
|
||
};
|
||
struct mem_cgroup_reclaim_cookie *partial = &reclaim;
|
||
struct mem_cgroup *memcg;
|
||
|
||
/*
|
||
* In most cases, direct reclaimers can do partial walks
|
||
* through the cgroup tree, using an iterator state that
|
||
* persists across invocations. This strikes a balance between
|
||
* fairness and allocation latency.
|
||
*
|
||
* For kswapd, reliable forward progress is more important
|
||
* than a quick return to idle. Always do full walks.
|
||
*/
|
||
if (current_is_kswapd() || sc->memcg_full_walk)
|
||
partial = NULL;
|
||
|
||
memcg = mem_cgroup_iter(target_memcg, NULL, partial);
|
||
do {
|
||
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
|
||
unsigned long reclaimed;
|
||
unsigned long scanned;
|
||
|
||
/*
|
||
* This loop can become CPU-bound when target memcgs
|
||
* aren't eligible for reclaim - either because they
|
||
* don't have any reclaimable pages, or because their
|
||
* memory is explicitly protected. Avoid soft lockups.
|
||
*/
|
||
cond_resched();
|
||
|
||
mem_cgroup_calculate_protection(target_memcg, memcg);
|
||
|
||
if (mem_cgroup_below_min(target_memcg, memcg)) {
|
||
/*
|
||
* Hard protection.
|
||
* If there is no reclaimable memory, OOM.
|
||
*/
|
||
continue;
|
||
} else if (mem_cgroup_below_low(target_memcg, memcg)) {
|
||
/*
|
||
* Soft protection.
|
||
* Respect the protection only as long as
|
||
* there is an unprotected supply
|
||
* of reclaimable memory from other cgroups.
|
||
*/
|
||
if (!sc->memcg_low_reclaim) {
|
||
sc->memcg_low_skipped = 1;
|
||
continue;
|
||
}
|
||
memcg_memory_event(memcg, MEMCG_LOW);
|
||
}
|
||
|
||
reclaimed = sc->nr_reclaimed;
|
||
scanned = sc->nr_scanned;
|
||
|
||
shrink_lruvec(lruvec, sc);
|
||
|
||
shrink_slab(sc->gfp_mask, pgdat->node_id, memcg,
|
||
sc->priority);
|
||
|
||
/* Record the group's reclaim efficiency */
|
||
if (!sc->proactive)
|
||
vmpressure(sc->gfp_mask, memcg, false,
|
||
sc->nr_scanned - scanned,
|
||
sc->nr_reclaimed - reclaimed);
|
||
|
||
/* If partial walks are allowed, bail once goal is reached */
|
||
if (partial && sc->nr_reclaimed >= sc->nr_to_reclaim) {
|
||
mem_cgroup_iter_break(target_memcg, memcg);
|
||
break;
|
||
}
|
||
} while ((memcg = mem_cgroup_iter(target_memcg, memcg, partial)));
|
||
}
|
||
|
||
static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)
|
||
{
|
||
unsigned long nr_reclaimed, nr_scanned, nr_node_reclaimed;
|
||
struct lruvec *target_lruvec;
|
||
bool reclaimable = false;
|
||
|
||
if (lru_gen_enabled() && root_reclaim(sc)) {
|
||
lru_gen_shrink_node(pgdat, sc);
|
||
return;
|
||
}
|
||
|
||
target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat);
|
||
|
||
again:
|
||
memset(&sc->nr, 0, sizeof(sc->nr));
|
||
|
||
nr_reclaimed = sc->nr_reclaimed;
|
||
nr_scanned = sc->nr_scanned;
|
||
|
||
prepare_scan_control(pgdat, sc);
|
||
|
||
shrink_node_memcgs(pgdat, sc);
|
||
|
||
flush_reclaim_state(sc);
|
||
|
||
nr_node_reclaimed = sc->nr_reclaimed - nr_reclaimed;
|
||
|
||
/* Record the subtree's reclaim efficiency */
|
||
if (!sc->proactive)
|
||
vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true,
|
||
sc->nr_scanned - nr_scanned, nr_node_reclaimed);
|
||
|
||
if (nr_node_reclaimed)
|
||
reclaimable = true;
|
||
|
||
if (current_is_kswapd()) {
|
||
/*
|
||
* If reclaim is isolating dirty pages under writeback,
|
||
* it implies that the long-lived page allocation rate
|
||
* is exceeding the page laundering rate. Either the
|
||
* global limits are not being effective at throttling
|
||
* processes due to the page distribution throughout
|
||
* zones or there is heavy usage of a slow backing
|
||
* device. The only option is to throttle from reclaim
|
||
* context which is not ideal as there is no guarantee
|
||
* the dirtying process is throttled in the same way
|
||
* balance_dirty_pages() manages.
|
||
*
|
||
* Once a node is flagged PGDAT_WRITEBACK, kswapd will
|
||
* count the number of pages under pages flagged for
|
||
* immediate reclaim and stall if any are encountered
|
||
* in the nr_immediate check below.
|
||
*/
|
||
if (sc->nr.writeback && sc->nr.writeback == sc->nr.taken)
|
||
set_bit(PGDAT_WRITEBACK, &pgdat->flags);
|
||
|
||
/* Allow kswapd to start writing pages during reclaim.*/
|
||
if (sc->nr.unqueued_dirty == sc->nr.file_taken)
|
||
set_bit(PGDAT_DIRTY, &pgdat->flags);
|
||
|
||
/*
|
||
* If kswapd scans pages marked for immediate
|
||
* reclaim and under writeback (nr_immediate), it
|
||
* implies that pages are cycling through the LRU
|
||
* faster than they are written so forcibly stall
|
||
* until some pages complete writeback.
|
||
*/
|
||
if (sc->nr.immediate)
|
||
reclaim_throttle(pgdat, VMSCAN_THROTTLE_WRITEBACK);
|
||
}
|
||
|
||
/*
|
||
* Tag a node/memcg as congested if all the dirty pages were marked
|
||
* for writeback and immediate reclaim (counted in nr.congested).
|
||
*
|
||
* Legacy memcg will stall in page writeback so avoid forcibly
|
||
* stalling in reclaim_throttle().
|
||
*/
|
||
if (sc->nr.dirty && sc->nr.dirty == sc->nr.congested) {
|
||
if (cgroup_reclaim(sc) && writeback_throttling_sane(sc))
|
||
set_bit(LRUVEC_CGROUP_CONGESTED, &target_lruvec->flags);
|
||
|
||
if (current_is_kswapd())
|
||
set_bit(LRUVEC_NODE_CONGESTED, &target_lruvec->flags);
|
||
}
|
||
|
||
/*
|
||
* Stall direct reclaim for IO completions if the lruvec is
|
||
* node is congested. Allow kswapd to continue until it
|
||
* starts encountering unqueued dirty pages or cycling through
|
||
* the LRU too quickly.
|
||
*/
|
||
if (!current_is_kswapd() && current_may_throttle() &&
|
||
!sc->hibernation_mode &&
|
||
(test_bit(LRUVEC_CGROUP_CONGESTED, &target_lruvec->flags) ||
|
||
test_bit(LRUVEC_NODE_CONGESTED, &target_lruvec->flags)))
|
||
reclaim_throttle(pgdat, VMSCAN_THROTTLE_CONGESTED);
|
||
|
||
if (should_continue_reclaim(pgdat, nr_node_reclaimed, sc))
|
||
goto again;
|
||
|
||
/*
|
||
* Kswapd gives up on balancing particular nodes after too
|
||
* many failures to reclaim anything from them and goes to
|
||
* sleep. On reclaim progress, reset the failure counter. A
|
||
* successful direct reclaim run will revive a dormant kswapd.
|
||
*/
|
||
if (reclaimable)
|
||
pgdat->kswapd_failures = 0;
|
||
else if (sc->cache_trim_mode)
|
||
sc->cache_trim_mode_failed = 1;
|
||
}
|
||
|
||
/*
|
||
* Returns true if compaction should go ahead for a costly-order request, or
|
||
* the allocation would already succeed without compaction. Return false if we
|
||
* should reclaim first.
|
||
*/
|
||
static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
|
||
{
|
||
unsigned long watermark;
|
||
|
||
if (!gfp_compaction_allowed(sc->gfp_mask))
|
||
return false;
|
||
|
||
/* Allocation can already succeed, nothing to do */
|
||
if (zone_watermark_ok(zone, sc->order, min_wmark_pages(zone),
|
||
sc->reclaim_idx, 0))
|
||
return true;
|
||
|
||
/* Compaction cannot yet proceed. Do reclaim. */
|
||
if (!compaction_suitable(zone, sc->order, sc->reclaim_idx))
|
||
return false;
|
||
|
||
/*
|
||
* Compaction is already possible, but it takes time to run and there
|
||
* are potentially other callers using the pages just freed. So proceed
|
||
* with reclaim to make a buffer of free pages available to give
|
||
* compaction a reasonable chance of completing and allocating the page.
|
||
* Note that we won't actually reclaim the whole buffer in one attempt
|
||
* as the target watermark in should_continue_reclaim() is lower. But if
|
||
* we are already above the high+gap watermark, don't reclaim at all.
|
||
*/
|
||
watermark = high_wmark_pages(zone) + compact_gap(sc->order);
|
||
|
||
return zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx);
|
||
}
|
||
|
||
static void consider_reclaim_throttle(pg_data_t *pgdat, struct scan_control *sc)
|
||
{
|
||
/*
|
||
* If reclaim is making progress greater than 12% efficiency then
|
||
* wake all the NOPROGRESS throttled tasks.
|
||
*/
|
||
if (sc->nr_reclaimed > (sc->nr_scanned >> 3)) {
|
||
wait_queue_head_t *wqh;
|
||
|
||
wqh = &pgdat->reclaim_wait[VMSCAN_THROTTLE_NOPROGRESS];
|
||
if (waitqueue_active(wqh))
|
||
wake_up(wqh);
|
||
|
||
return;
|
||
}
|
||
|
||
/*
|
||
* Do not throttle kswapd or cgroup reclaim on NOPROGRESS as it will
|
||
* throttle on VMSCAN_THROTTLE_WRITEBACK if there are too many pages
|
||
* under writeback and marked for immediate reclaim at the tail of the
|
||
* LRU.
|
||
*/
|
||
if (current_is_kswapd() || cgroup_reclaim(sc))
|
||
return;
|
||
|
||
/* Throttle if making no progress at high prioities. */
|
||
if (sc->priority == 1 && !sc->nr_reclaimed)
|
||
reclaim_throttle(pgdat, VMSCAN_THROTTLE_NOPROGRESS);
|
||
}
|
||
|
||
/*
|
||
* This is the direct reclaim path, for page-allocating processes. We only
|
||
* try to reclaim pages from zones which will satisfy the caller's allocation
|
||
* request.
|
||
*
|
||
* If a zone is deemed to be full of pinned pages then just give it a light
|
||
* scan then give up on it.
|
||
*/
|
||
static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
|
||
{
|
||
struct zoneref *z;
|
||
struct zone *zone;
|
||
unsigned long nr_soft_reclaimed;
|
||
unsigned long nr_soft_scanned;
|
||
gfp_t orig_mask;
|
||
pg_data_t *last_pgdat = NULL;
|
||
pg_data_t *first_pgdat = NULL;
|
||
|
||
/*
|
||
* If the number of buffer_heads in the machine exceeds the maximum
|
||
* allowed level, force direct reclaim to scan the highmem zone as
|
||
* highmem pages could be pinning lowmem pages storing buffer_heads
|
||
*/
|
||
orig_mask = sc->gfp_mask;
|
||
if (buffer_heads_over_limit) {
|
||
sc->gfp_mask |= __GFP_HIGHMEM;
|
||
sc->reclaim_idx = gfp_zone(sc->gfp_mask);
|
||
}
|
||
|
||
for_each_zone_zonelist_nodemask(zone, z, zonelist,
|
||
sc->reclaim_idx, sc->nodemask) {
|
||
/*
|
||
* Take care memory controller reclaiming has small influence
|
||
* to global LRU.
|
||
*/
|
||
if (!cgroup_reclaim(sc)) {
|
||
if (!cpuset_zone_allowed(zone,
|
||
GFP_KERNEL | __GFP_HARDWALL))
|
||
continue;
|
||
|
||
/*
|
||
* If we already have plenty of memory free for
|
||
* compaction in this zone, don't free any more.
|
||
* Even though compaction is invoked for any
|
||
* non-zero order, only frequent costly order
|
||
* reclamation is disruptive enough to become a
|
||
* noticeable problem, like transparent huge
|
||
* page allocations.
|
||
*/
|
||
if (IS_ENABLED(CONFIG_COMPACTION) &&
|
||
sc->order > PAGE_ALLOC_COSTLY_ORDER &&
|
||
compaction_ready(zone, sc)) {
|
||
sc->compaction_ready = true;
|
||
continue;
|
||
}
|
||
|
||
/*
|
||
* Shrink each node in the zonelist once. If the
|
||
* zonelist is ordered by zone (not the default) then a
|
||
* node may be shrunk multiple times but in that case
|
||
* the user prefers lower zones being preserved.
|
||
*/
|
||
if (zone->zone_pgdat == last_pgdat)
|
||
continue;
|
||
|
||
/*
|
||
* This steals pages from memory cgroups over softlimit
|
||
* and returns the number of reclaimed pages and
|
||
* scanned pages. This works for global memory pressure
|
||
* and balancing, not for a memcg's limit.
|
||
*/
|
||
nr_soft_scanned = 0;
|
||
nr_soft_reclaimed = memcg1_soft_limit_reclaim(zone->zone_pgdat,
|
||
sc->order, sc->gfp_mask,
|
||
&nr_soft_scanned);
|
||
sc->nr_reclaimed += nr_soft_reclaimed;
|
||
sc->nr_scanned += nr_soft_scanned;
|
||
/* need some check for avoid more shrink_zone() */
|
||
}
|
||
|
||
if (!first_pgdat)
|
||
first_pgdat = zone->zone_pgdat;
|
||
|
||
/* See comment about same check for global reclaim above */
|
||
if (zone->zone_pgdat == last_pgdat)
|
||
continue;
|
||
last_pgdat = zone->zone_pgdat;
|
||
shrink_node(zone->zone_pgdat, sc);
|
||
}
|
||
|
||
if (first_pgdat)
|
||
consider_reclaim_throttle(first_pgdat, sc);
|
||
|
||
/*
|
||
* Restore to original mask to avoid the impact on the caller if we
|
||
* promoted it to __GFP_HIGHMEM.
|
||
*/
|
||
sc->gfp_mask = orig_mask;
|
||
}
|
||
|
||
static void snapshot_refaults(struct mem_cgroup *target_memcg, pg_data_t *pgdat)
|
||
{
|
||
struct lruvec *target_lruvec;
|
||
unsigned long refaults;
|
||
|
||
if (lru_gen_enabled())
|
||
return;
|
||
|
||
target_lruvec = mem_cgroup_lruvec(target_memcg, pgdat);
|
||
refaults = lruvec_page_state(target_lruvec, WORKINGSET_ACTIVATE_ANON);
|
||
target_lruvec->refaults[WORKINGSET_ANON] = refaults;
|
||
refaults = lruvec_page_state(target_lruvec, WORKINGSET_ACTIVATE_FILE);
|
||
target_lruvec->refaults[WORKINGSET_FILE] = refaults;
|
||
}
|
||
|
||
/*
|
||
* This is the main entry point to direct page reclaim.
|
||
*
|
||
* If a full scan of the inactive list fails to free enough memory then we
|
||
* are "out of memory" and something needs to be killed.
|
||
*
|
||
* If the caller is !__GFP_FS then the probability of a failure is reasonably
|
||
* high - the zone may be full of dirty or under-writeback pages, which this
|
||
* caller can't do much about. We kick the writeback threads and take explicit
|
||
* naps in the hope that some of these pages can be written. But if the
|
||
* allocating task holds filesystem locks which prevent writeout this might not
|
||
* work, and the allocation attempt will fail.
|
||
*
|
||
* returns: 0, if no pages reclaimed
|
||
* else, the number of pages reclaimed
|
||
*/
|
||
static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
|
||
struct scan_control *sc)
|
||
{
|
||
int initial_priority = sc->priority;
|
||
pg_data_t *last_pgdat;
|
||
struct zoneref *z;
|
||
struct zone *zone;
|
||
retry:
|
||
delayacct_freepages_start();
|
||
|
||
if (!cgroup_reclaim(sc))
|
||
__count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1);
|
||
|
||
do {
|
||
if (!sc->proactive)
|
||
vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
|
||
sc->priority);
|
||
sc->nr_scanned = 0;
|
||
shrink_zones(zonelist, sc);
|
||
|
||
if (sc->nr_reclaimed >= sc->nr_to_reclaim)
|
||
break;
|
||
|
||
if (sc->compaction_ready)
|
||
break;
|
||
|
||
/*
|
||
* If we're getting trouble reclaiming, start doing
|
||
* writepage even in laptop mode.
|
||
*/
|
||
if (sc->priority < DEF_PRIORITY - 2)
|
||
sc->may_writepage = 1;
|
||
} while (--sc->priority >= 0);
|
||
|
||
last_pgdat = NULL;
|
||
for_each_zone_zonelist_nodemask(zone, z, zonelist, sc->reclaim_idx,
|
||
sc->nodemask) {
|
||
if (zone->zone_pgdat == last_pgdat)
|
||
continue;
|
||
last_pgdat = zone->zone_pgdat;
|
||
|
||
snapshot_refaults(sc->target_mem_cgroup, zone->zone_pgdat);
|
||
|
||
if (cgroup_reclaim(sc)) {
|
||
struct lruvec *lruvec;
|
||
|
||
lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup,
|
||
zone->zone_pgdat);
|
||
clear_bit(LRUVEC_CGROUP_CONGESTED, &lruvec->flags);
|
||
}
|
||
}
|
||
|
||
delayacct_freepages_end();
|
||
|
||
if (sc->nr_reclaimed)
|
||
return sc->nr_reclaimed;
|
||
|
||
/* Aborted reclaim to try compaction? don't OOM, then */
|
||
if (sc->compaction_ready)
|
||
return 1;
|
||
|
||
/*
|
||
* In most cases, direct reclaimers can do partial walks
|
||
* through the cgroup tree to meet the reclaim goal while
|
||
* keeping latency low. Since the iterator state is shared
|
||
* among all direct reclaim invocations (to retain fairness
|
||
* among cgroups), though, high concurrency can result in
|
||
* individual threads not seeing enough cgroups to make
|
||
* meaningful forward progress. Avoid false OOMs in this case.
|
||
*/
|
||
if (!sc->memcg_full_walk) {
|
||
sc->priority = initial_priority;
|
||
sc->memcg_full_walk = 1;
|
||
goto retry;
|
||
}
|
||
|
||
/*
|
||
* We make inactive:active ratio decisions based on the node's
|
||
* composition of memory, but a restrictive reclaim_idx or a
|
||
* memory.low cgroup setting can exempt large amounts of
|
||
* memory from reclaim. Neither of which are very common, so
|
||
* instead of doing costly eligibility calculations of the
|
||
* entire cgroup subtree up front, we assume the estimates are
|
||
* good, and retry with forcible deactivation if that fails.
|
||
*/
|
||
if (sc->skipped_deactivate) {
|
||
sc->priority = initial_priority;
|
||
sc->force_deactivate = 1;
|
||
sc->skipped_deactivate = 0;
|
||
goto retry;
|
||
}
|
||
|
||
/* Untapped cgroup reserves? Don't OOM, retry. */
|
||
if (sc->memcg_low_skipped) {
|
||
sc->priority = initial_priority;
|
||
sc->force_deactivate = 0;
|
||
sc->memcg_low_reclaim = 1;
|
||
sc->memcg_low_skipped = 0;
|
||
goto retry;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
static bool allow_direct_reclaim(pg_data_t *pgdat)
|
||
{
|
||
struct zone *zone;
|
||
unsigned long pfmemalloc_reserve = 0;
|
||
unsigned long free_pages = 0;
|
||
int i;
|
||
bool wmark_ok;
|
||
|
||
if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES)
|
||
return true;
|
||
|
||
for (i = 0; i <= ZONE_NORMAL; i++) {
|
||
zone = &pgdat->node_zones[i];
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
if (!zone_reclaimable_pages(zone))
|
||
continue;
|
||
|
||
pfmemalloc_reserve += min_wmark_pages(zone);
|
||
free_pages += zone_page_state_snapshot(zone, NR_FREE_PAGES);
|
||
}
|
||
|
||
/* If there are no reserves (unexpected config) then do not throttle */
|
||
if (!pfmemalloc_reserve)
|
||
return true;
|
||
|
||
wmark_ok = free_pages > pfmemalloc_reserve / 2;
|
||
|
||
/* kswapd must be awake if processes are being throttled */
|
||
if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) {
|
||
if (READ_ONCE(pgdat->kswapd_highest_zoneidx) > ZONE_NORMAL)
|
||
WRITE_ONCE(pgdat->kswapd_highest_zoneidx, ZONE_NORMAL);
|
||
|
||
wake_up_interruptible(&pgdat->kswapd_wait);
|
||
}
|
||
|
||
return wmark_ok;
|
||
}
|
||
|
||
/*
|
||
* Throttle direct reclaimers if backing storage is backed by the network
|
||
* and the PFMEMALLOC reserve for the preferred node is getting dangerously
|
||
* depleted. kswapd will continue to make progress and wake the processes
|
||
* when the low watermark is reached.
|
||
*
|
||
* Returns true if a fatal signal was delivered during throttling. If this
|
||
* happens, the page allocator should not consider triggering the OOM killer.
|
||
*/
|
||
static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
|
||
nodemask_t *nodemask)
|
||
{
|
||
struct zoneref *z;
|
||
struct zone *zone;
|
||
pg_data_t *pgdat = NULL;
|
||
|
||
/*
|
||
* Kernel threads should not be throttled as they may be indirectly
|
||
* responsible for cleaning pages necessary for reclaim to make forward
|
||
* progress. kjournald for example may enter direct reclaim while
|
||
* committing a transaction where throttling it could forcing other
|
||
* processes to block on log_wait_commit().
|
||
*/
|
||
if (current->flags & PF_KTHREAD)
|
||
goto out;
|
||
|
||
/*
|
||
* If a fatal signal is pending, this process should not throttle.
|
||
* It should return quickly so it can exit and free its memory
|
||
*/
|
||
if (fatal_signal_pending(current))
|
||
goto out;
|
||
|
||
/*
|
||
* Check if the pfmemalloc reserves are ok by finding the first node
|
||
* with a usable ZONE_NORMAL or lower zone. The expectation is that
|
||
* GFP_KERNEL will be required for allocating network buffers when
|
||
* swapping over the network so ZONE_HIGHMEM is unusable.
|
||
*
|
||
* Throttling is based on the first usable node and throttled processes
|
||
* wait on a queue until kswapd makes progress and wakes them. There
|
||
* is an affinity then between processes waking up and where reclaim
|
||
* progress has been made assuming the process wakes on the same node.
|
||
* More importantly, processes running on remote nodes will not compete
|
||
* for remote pfmemalloc reserves and processes on different nodes
|
||
* should make reasonable progress.
|
||
*/
|
||
for_each_zone_zonelist_nodemask(zone, z, zonelist,
|
||
gfp_zone(gfp_mask), nodemask) {
|
||
if (zone_idx(zone) > ZONE_NORMAL)
|
||
continue;
|
||
|
||
/* Throttle based on the first usable node */
|
||
pgdat = zone->zone_pgdat;
|
||
if (allow_direct_reclaim(pgdat))
|
||
goto out;
|
||
break;
|
||
}
|
||
|
||
/* If no zone was usable by the allocation flags then do not throttle */
|
||
if (!pgdat)
|
||
goto out;
|
||
|
||
/* Account for the throttling */
|
||
count_vm_event(PGSCAN_DIRECT_THROTTLE);
|
||
|
||
/*
|
||
* If the caller cannot enter the filesystem, it's possible that it
|
||
* is due to the caller holding an FS lock or performing a journal
|
||
* transaction in the case of a filesystem like ext[3|4]. In this case,
|
||
* it is not safe to block on pfmemalloc_wait as kswapd could be
|
||
* blocked waiting on the same lock. Instead, throttle for up to a
|
||
* second before continuing.
|
||
*/
|
||
if (!(gfp_mask & __GFP_FS))
|
||
wait_event_interruptible_timeout(pgdat->pfmemalloc_wait,
|
||
allow_direct_reclaim(pgdat), HZ);
|
||
else
|
||
/* Throttle until kswapd wakes the process */
|
||
wait_event_killable(zone->zone_pgdat->pfmemalloc_wait,
|
||
allow_direct_reclaim(pgdat));
|
||
|
||
if (fatal_signal_pending(current))
|
||
return true;
|
||
|
||
out:
|
||
return false;
|
||
}
|
||
|
||
unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
|
||
gfp_t gfp_mask, nodemask_t *nodemask)
|
||
{
|
||
unsigned long nr_reclaimed;
|
||
struct scan_control sc = {
|
||
.nr_to_reclaim = SWAP_CLUSTER_MAX,
|
||
.gfp_mask = current_gfp_context(gfp_mask),
|
||
.reclaim_idx = gfp_zone(gfp_mask),
|
||
.order = order,
|
||
.nodemask = nodemask,
|
||
.priority = DEF_PRIORITY,
|
||
.may_writepage = !laptop_mode,
|
||
.may_unmap = 1,
|
||
.may_swap = 1,
|
||
};
|
||
|
||
/*
|
||
* scan_control uses s8 fields for order, priority, and reclaim_idx.
|
||
* Confirm they are large enough for max values.
|
||
*/
|
||
BUILD_BUG_ON(MAX_PAGE_ORDER >= S8_MAX);
|
||
BUILD_BUG_ON(DEF_PRIORITY > S8_MAX);
|
||
BUILD_BUG_ON(MAX_NR_ZONES > S8_MAX);
|
||
|
||
/*
|
||
* Do not enter reclaim if fatal signal was delivered while throttled.
|
||
* 1 is returned so that the page allocator does not OOM kill at this
|
||
* point.
|
||
*/
|
||
if (throttle_direct_reclaim(sc.gfp_mask, zonelist, nodemask))
|
||
return 1;
|
||
|
||
set_task_reclaim_state(current, &sc.reclaim_state);
|
||
trace_mm_vmscan_direct_reclaim_begin(order, sc.gfp_mask);
|
||
|
||
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
|
||
|
||
trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
|
||
set_task_reclaim_state(current, NULL);
|
||
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
|
||
/* Only used by soft limit reclaim. Do not reuse for anything else. */
|
||
unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
|
||
gfp_t gfp_mask, bool noswap,
|
||
pg_data_t *pgdat,
|
||
unsigned long *nr_scanned)
|
||
{
|
||
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
|
||
struct scan_control sc = {
|
||
.nr_to_reclaim = SWAP_CLUSTER_MAX,
|
||
.target_mem_cgroup = memcg,
|
||
.may_writepage = !laptop_mode,
|
||
.may_unmap = 1,
|
||
.reclaim_idx = MAX_NR_ZONES - 1,
|
||
.may_swap = !noswap,
|
||
};
|
||
|
||
WARN_ON_ONCE(!current->reclaim_state);
|
||
|
||
sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
|
||
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
|
||
|
||
trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order,
|
||
sc.gfp_mask);
|
||
|
||
/*
|
||
* NOTE: Although we can get the priority field, using it
|
||
* here is not a good idea, since it limits the pages we can scan.
|
||
* if we don't reclaim here, the shrink_node from balance_pgdat
|
||
* will pick up pages from other mem cgroup's as well. We hack
|
||
* the priority and make it zero.
|
||
*/
|
||
shrink_lruvec(lruvec, &sc);
|
||
|
||
trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
|
||
|
||
*nr_scanned = sc.nr_scanned;
|
||
|
||
return sc.nr_reclaimed;
|
||
}
|
||
|
||
unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
|
||
unsigned long nr_pages,
|
||
gfp_t gfp_mask,
|
||
unsigned int reclaim_options,
|
||
int *swappiness)
|
||
{
|
||
unsigned long nr_reclaimed;
|
||
unsigned int noreclaim_flag;
|
||
struct scan_control sc = {
|
||
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
|
||
.proactive_swappiness = swappiness,
|
||
.gfp_mask = (current_gfp_context(gfp_mask) & GFP_RECLAIM_MASK) |
|
||
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
|
||
.reclaim_idx = MAX_NR_ZONES - 1,
|
||
.target_mem_cgroup = memcg,
|
||
.priority = DEF_PRIORITY,
|
||
.may_writepage = !laptop_mode,
|
||
.may_unmap = 1,
|
||
.may_swap = !!(reclaim_options & MEMCG_RECLAIM_MAY_SWAP),
|
||
.proactive = !!(reclaim_options & MEMCG_RECLAIM_PROACTIVE),
|
||
};
|
||
/*
|
||
* Traverse the ZONELIST_FALLBACK zonelist of the current node to put
|
||
* equal pressure on all the nodes. This is based on the assumption that
|
||
* the reclaim does not bail out early.
|
||
*/
|
||
struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
|
||
|
||
set_task_reclaim_state(current, &sc.reclaim_state);
|
||
trace_mm_vmscan_memcg_reclaim_begin(0, sc.gfp_mask);
|
||
noreclaim_flag = memalloc_noreclaim_save();
|
||
|
||
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
|
||
|
||
memalloc_noreclaim_restore(noreclaim_flag);
|
||
trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
|
||
set_task_reclaim_state(current, NULL);
|
||
|
||
return nr_reclaimed;
|
||
}
|
||
#endif
|
||
|
||
static void kswapd_age_node(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
struct mem_cgroup *memcg;
|
||
struct lruvec *lruvec;
|
||
|
||
if (lru_gen_enabled()) {
|
||
lru_gen_age_node(pgdat, sc);
|
||
return;
|
||
}
|
||
|
||
if (!can_age_anon_pages(pgdat, sc))
|
||
return;
|
||
|
||
lruvec = mem_cgroup_lruvec(NULL, pgdat);
|
||
if (!inactive_is_low(lruvec, LRU_INACTIVE_ANON))
|
||
return;
|
||
|
||
memcg = mem_cgroup_iter(NULL, NULL, NULL);
|
||
do {
|
||
lruvec = mem_cgroup_lruvec(memcg, pgdat);
|
||
shrink_active_list(SWAP_CLUSTER_MAX, lruvec,
|
||
sc, LRU_ACTIVE_ANON);
|
||
memcg = mem_cgroup_iter(NULL, memcg, NULL);
|
||
} while (memcg);
|
||
}
|
||
|
||
static bool pgdat_watermark_boosted(pg_data_t *pgdat, int highest_zoneidx)
|
||
{
|
||
int i;
|
||
struct zone *zone;
|
||
|
||
/*
|
||
* Check for watermark boosts top-down as the higher zones
|
||
* are more likely to be boosted. Both watermarks and boosts
|
||
* should not be checked at the same time as reclaim would
|
||
* start prematurely when there is no boosting and a lower
|
||
* zone is balanced.
|
||
*/
|
||
for (i = highest_zoneidx; i >= 0; i--) {
|
||
zone = pgdat->node_zones + i;
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
if (zone->watermark_boost)
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
/*
|
||
* Returns true if there is an eligible zone balanced for the request order
|
||
* and highest_zoneidx
|
||
*/
|
||
static bool pgdat_balanced(pg_data_t *pgdat, int order, int highest_zoneidx)
|
||
{
|
||
int i;
|
||
unsigned long mark = -1;
|
||
struct zone *zone;
|
||
|
||
/*
|
||
* Check watermarks bottom-up as lower zones are more likely to
|
||
* meet watermarks.
|
||
*/
|
||
for (i = 0; i <= highest_zoneidx; i++) {
|
||
zone = pgdat->node_zones + i;
|
||
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING)
|
||
mark = promo_wmark_pages(zone);
|
||
else
|
||
mark = high_wmark_pages(zone);
|
||
if (zone_watermark_ok_safe(zone, order, mark, highest_zoneidx))
|
||
return true;
|
||
}
|
||
|
||
/*
|
||
* If a node has no managed zone within highest_zoneidx, it does not
|
||
* need balancing by definition. This can happen if a zone-restricted
|
||
* allocation tries to wake a remote kswapd.
|
||
*/
|
||
if (mark == -1)
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
/* Clear pgdat state for congested, dirty or under writeback. */
|
||
static void clear_pgdat_congested(pg_data_t *pgdat)
|
||
{
|
||
struct lruvec *lruvec = mem_cgroup_lruvec(NULL, pgdat);
|
||
|
||
clear_bit(LRUVEC_NODE_CONGESTED, &lruvec->flags);
|
||
clear_bit(LRUVEC_CGROUP_CONGESTED, &lruvec->flags);
|
||
clear_bit(PGDAT_DIRTY, &pgdat->flags);
|
||
clear_bit(PGDAT_WRITEBACK, &pgdat->flags);
|
||
}
|
||
|
||
/*
|
||
* Prepare kswapd for sleeping. This verifies that there are no processes
|
||
* waiting in throttle_direct_reclaim() and that watermarks have been met.
|
||
*
|
||
* Returns true if kswapd is ready to sleep
|
||
*/
|
||
static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order,
|
||
int highest_zoneidx)
|
||
{
|
||
/*
|
||
* The throttled processes are normally woken up in balance_pgdat() as
|
||
* soon as allow_direct_reclaim() is true. But there is a potential
|
||
* race between when kswapd checks the watermarks and a process gets
|
||
* throttled. There is also a potential race if processes get
|
||
* throttled, kswapd wakes, a large process exits thereby balancing the
|
||
* zones, which causes kswapd to exit balance_pgdat() before reaching
|
||
* the wake up checks. If kswapd is going to sleep, no process should
|
||
* be sleeping on pfmemalloc_wait, so wake them now if necessary. If
|
||
* the wake up is premature, processes will wake kswapd and get
|
||
* throttled again. The difference from wake ups in balance_pgdat() is
|
||
* that here we are under prepare_to_wait().
|
||
*/
|
||
if (waitqueue_active(&pgdat->pfmemalloc_wait))
|
||
wake_up_all(&pgdat->pfmemalloc_wait);
|
||
|
||
/* Hopeless node, leave it to direct reclaim */
|
||
if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES)
|
||
return true;
|
||
|
||
if (pgdat_balanced(pgdat, order, highest_zoneidx)) {
|
||
clear_pgdat_congested(pgdat);
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
/*
|
||
* kswapd shrinks a node of pages that are at or below the highest usable
|
||
* zone that is currently unbalanced.
|
||
*
|
||
* Returns true if kswapd scanned at least the requested number of pages to
|
||
* reclaim or if the lack of progress was due to pages under writeback.
|
||
* This is used to determine if the scanning priority needs to be raised.
|
||
*/
|
||
static bool kswapd_shrink_node(pg_data_t *pgdat,
|
||
struct scan_control *sc)
|
||
{
|
||
struct zone *zone;
|
||
int z;
|
||
unsigned long nr_reclaimed = sc->nr_reclaimed;
|
||
|
||
/* Reclaim a number of pages proportional to the number of zones */
|
||
sc->nr_to_reclaim = 0;
|
||
for (z = 0; z <= sc->reclaim_idx; z++) {
|
||
zone = pgdat->node_zones + z;
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
sc->nr_to_reclaim += max(high_wmark_pages(zone), SWAP_CLUSTER_MAX);
|
||
}
|
||
|
||
/*
|
||
* Historically care was taken to put equal pressure on all zones but
|
||
* now pressure is applied based on node LRU order.
|
||
*/
|
||
shrink_node(pgdat, sc);
|
||
|
||
/*
|
||
* Fragmentation may mean that the system cannot be rebalanced for
|
||
* high-order allocations. If twice the allocation size has been
|
||
* reclaimed then recheck watermarks only at order-0 to prevent
|
||
* excessive reclaim. Assume that a process requested a high-order
|
||
* can direct reclaim/compact.
|
||
*/
|
||
if (sc->order && sc->nr_reclaimed >= compact_gap(sc->order))
|
||
sc->order = 0;
|
||
|
||
/* account for progress from mm_account_reclaimed_pages() */
|
||
return max(sc->nr_scanned, sc->nr_reclaimed - nr_reclaimed) >= sc->nr_to_reclaim;
|
||
}
|
||
|
||
/* Page allocator PCP high watermark is lowered if reclaim is active. */
|
||
static inline void
|
||
update_reclaim_active(pg_data_t *pgdat, int highest_zoneidx, bool active)
|
||
{
|
||
int i;
|
||
struct zone *zone;
|
||
|
||
for (i = 0; i <= highest_zoneidx; i++) {
|
||
zone = pgdat->node_zones + i;
|
||
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
if (active)
|
||
set_bit(ZONE_RECLAIM_ACTIVE, &zone->flags);
|
||
else
|
||
clear_bit(ZONE_RECLAIM_ACTIVE, &zone->flags);
|
||
}
|
||
}
|
||
|
||
static inline void
|
||
set_reclaim_active(pg_data_t *pgdat, int highest_zoneidx)
|
||
{
|
||
update_reclaim_active(pgdat, highest_zoneidx, true);
|
||
}
|
||
|
||
static inline void
|
||
clear_reclaim_active(pg_data_t *pgdat, int highest_zoneidx)
|
||
{
|
||
update_reclaim_active(pgdat, highest_zoneidx, false);
|
||
}
|
||
|
||
/*
|
||
* For kswapd, balance_pgdat() will reclaim pages across a node from zones
|
||
* that are eligible for use by the caller until at least one zone is
|
||
* balanced.
|
||
*
|
||
* Returns the order kswapd finished reclaiming at.
|
||
*
|
||
* kswapd scans the zones in the highmem->normal->dma direction. It skips
|
||
* zones which have free_pages > high_wmark_pages(zone), but once a zone is
|
||
* found to have free_pages <= high_wmark_pages(zone), any page in that zone
|
||
* or lower is eligible for reclaim until at least one usable zone is
|
||
* balanced.
|
||
*/
|
||
static int balance_pgdat(pg_data_t *pgdat, int order, int highest_zoneidx)
|
||
{
|
||
int i;
|
||
unsigned long nr_soft_reclaimed;
|
||
unsigned long nr_soft_scanned;
|
||
unsigned long pflags;
|
||
unsigned long nr_boost_reclaim;
|
||
unsigned long zone_boosts[MAX_NR_ZONES] = { 0, };
|
||
bool boosted;
|
||
struct zone *zone;
|
||
struct scan_control sc = {
|
||
.gfp_mask = GFP_KERNEL,
|
||
.order = order,
|
||
.may_unmap = 1,
|
||
};
|
||
|
||
set_task_reclaim_state(current, &sc.reclaim_state);
|
||
psi_memstall_enter(&pflags);
|
||
__fs_reclaim_acquire(_THIS_IP_);
|
||
|
||
count_vm_event(PAGEOUTRUN);
|
||
|
||
/*
|
||
* Account for the reclaim boost. Note that the zone boost is left in
|
||
* place so that parallel allocations that are near the watermark will
|
||
* stall or direct reclaim until kswapd is finished.
|
||
*/
|
||
nr_boost_reclaim = 0;
|
||
for (i = 0; i <= highest_zoneidx; i++) {
|
||
zone = pgdat->node_zones + i;
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
nr_boost_reclaim += zone->watermark_boost;
|
||
zone_boosts[i] = zone->watermark_boost;
|
||
}
|
||
boosted = nr_boost_reclaim;
|
||
|
||
restart:
|
||
set_reclaim_active(pgdat, highest_zoneidx);
|
||
sc.priority = DEF_PRIORITY;
|
||
do {
|
||
unsigned long nr_reclaimed = sc.nr_reclaimed;
|
||
bool raise_priority = true;
|
||
bool balanced;
|
||
bool ret;
|
||
bool was_frozen;
|
||
|
||
sc.reclaim_idx = highest_zoneidx;
|
||
|
||
/*
|
||
* If the number of buffer_heads exceeds the maximum allowed
|
||
* then consider reclaiming from all zones. This has a dual
|
||
* purpose -- on 64-bit systems it is expected that
|
||
* buffer_heads are stripped during active rotation. On 32-bit
|
||
* systems, highmem pages can pin lowmem memory and shrinking
|
||
* buffers can relieve lowmem pressure. Reclaim may still not
|
||
* go ahead if all eligible zones for the original allocation
|
||
* request are balanced to avoid excessive reclaim from kswapd.
|
||
*/
|
||
if (buffer_heads_over_limit) {
|
||
for (i = MAX_NR_ZONES - 1; i >= 0; i--) {
|
||
zone = pgdat->node_zones + i;
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
sc.reclaim_idx = i;
|
||
break;
|
||
}
|
||
}
|
||
|
||
/*
|
||
* If the pgdat is imbalanced then ignore boosting and preserve
|
||
* the watermarks for a later time and restart. Note that the
|
||
* zone watermarks will be still reset at the end of balancing
|
||
* on the grounds that the normal reclaim should be enough to
|
||
* re-evaluate if boosting is required when kswapd next wakes.
|
||
*/
|
||
balanced = pgdat_balanced(pgdat, sc.order, highest_zoneidx);
|
||
if (!balanced && nr_boost_reclaim) {
|
||
nr_boost_reclaim = 0;
|
||
goto restart;
|
||
}
|
||
|
||
/*
|
||
* If boosting is not active then only reclaim if there are no
|
||
* eligible zones. Note that sc.reclaim_idx is not used as
|
||
* buffer_heads_over_limit may have adjusted it.
|
||
*/
|
||
if (!nr_boost_reclaim && balanced)
|
||
goto out;
|
||
|
||
/* Limit the priority of boosting to avoid reclaim writeback */
|
||
if (nr_boost_reclaim && sc.priority == DEF_PRIORITY - 2)
|
||
raise_priority = false;
|
||
|
||
/*
|
||
* Do not writeback or swap pages for boosted reclaim. The
|
||
* intent is to relieve pressure not issue sub-optimal IO
|
||
* from reclaim context. If no pages are reclaimed, the
|
||
* reclaim will be aborted.
|
||
*/
|
||
sc.may_writepage = !laptop_mode && !nr_boost_reclaim;
|
||
sc.may_swap = !nr_boost_reclaim;
|
||
|
||
/*
|
||
* Do some background aging, to give pages a chance to be
|
||
* referenced before reclaiming. All pages are rotated
|
||
* regardless of classzone as this is about consistent aging.
|
||
*/
|
||
kswapd_age_node(pgdat, &sc);
|
||
|
||
/*
|
||
* If we're getting trouble reclaiming, start doing writepage
|
||
* even in laptop mode.
|
||
*/
|
||
if (sc.priority < DEF_PRIORITY - 2)
|
||
sc.may_writepage = 1;
|
||
|
||
/* Call soft limit reclaim before calling shrink_node. */
|
||
sc.nr_scanned = 0;
|
||
nr_soft_scanned = 0;
|
||
nr_soft_reclaimed = memcg1_soft_limit_reclaim(pgdat, sc.order,
|
||
sc.gfp_mask, &nr_soft_scanned);
|
||
sc.nr_reclaimed += nr_soft_reclaimed;
|
||
|
||
/*
|
||
* There should be no need to raise the scanning priority if
|
||
* enough pages are already being scanned that that high
|
||
* watermark would be met at 100% efficiency.
|
||
*/
|
||
if (kswapd_shrink_node(pgdat, &sc))
|
||
raise_priority = false;
|
||
|
||
/*
|
||
* If the low watermark is met there is no need for processes
|
||
* to be throttled on pfmemalloc_wait as they should not be
|
||
* able to safely make forward progress. Wake them
|
||
*/
|
||
if (waitqueue_active(&pgdat->pfmemalloc_wait) &&
|
||
allow_direct_reclaim(pgdat))
|
||
wake_up_all(&pgdat->pfmemalloc_wait);
|
||
|
||
/* Check if kswapd should be suspending */
|
||
__fs_reclaim_release(_THIS_IP_);
|
||
ret = kthread_freezable_should_stop(&was_frozen);
|
||
__fs_reclaim_acquire(_THIS_IP_);
|
||
if (was_frozen || ret)
|
||
break;
|
||
|
||
/*
|
||
* Raise priority if scanning rate is too low or there was no
|
||
* progress in reclaiming pages
|
||
*/
|
||
nr_reclaimed = sc.nr_reclaimed - nr_reclaimed;
|
||
nr_boost_reclaim -= min(nr_boost_reclaim, nr_reclaimed);
|
||
|
||
/*
|
||
* If reclaim made no progress for a boost, stop reclaim as
|
||
* IO cannot be queued and it could be an infinite loop in
|
||
* extreme circumstances.
|
||
*/
|
||
if (nr_boost_reclaim && !nr_reclaimed)
|
||
break;
|
||
|
||
if (raise_priority || !nr_reclaimed)
|
||
sc.priority--;
|
||
} while (sc.priority >= 1);
|
||
|
||
/*
|
||
* Restart only if it went through the priority loop all the way,
|
||
* but cache_trim_mode didn't work.
|
||
*/
|
||
if (!sc.nr_reclaimed && sc.priority < 1 &&
|
||
!sc.no_cache_trim_mode && sc.cache_trim_mode_failed) {
|
||
sc.no_cache_trim_mode = 1;
|
||
goto restart;
|
||
}
|
||
|
||
if (!sc.nr_reclaimed)
|
||
pgdat->kswapd_failures++;
|
||
|
||
out:
|
||
clear_reclaim_active(pgdat, highest_zoneidx);
|
||
|
||
/* If reclaim was boosted, account for the reclaim done in this pass */
|
||
if (boosted) {
|
||
unsigned long flags;
|
||
|
||
for (i = 0; i <= highest_zoneidx; i++) {
|
||
if (!zone_boosts[i])
|
||
continue;
|
||
|
||
/* Increments are under the zone lock */
|
||
zone = pgdat->node_zones + i;
|
||
spin_lock_irqsave(&zone->lock, flags);
|
||
zone->watermark_boost -= min(zone->watermark_boost, zone_boosts[i]);
|
||
spin_unlock_irqrestore(&zone->lock, flags);
|
||
}
|
||
|
||
/*
|
||
* As there is now likely space, wakeup kcompact to defragment
|
||
* pageblocks.
|
||
*/
|
||
wakeup_kcompactd(pgdat, pageblock_order, highest_zoneidx);
|
||
}
|
||
|
||
snapshot_refaults(NULL, pgdat);
|
||
__fs_reclaim_release(_THIS_IP_);
|
||
psi_memstall_leave(&pflags);
|
||
set_task_reclaim_state(current, NULL);
|
||
|
||
/*
|
||
* Return the order kswapd stopped reclaiming at as
|
||
* prepare_kswapd_sleep() takes it into account. If another caller
|
||
* entered the allocator slow path while kswapd was awake, order will
|
||
* remain at the higher level.
|
||
*/
|
||
return sc.order;
|
||
}
|
||
|
||
/*
|
||
* The pgdat->kswapd_highest_zoneidx is used to pass the highest zone index to
|
||
* be reclaimed by kswapd from the waker. If the value is MAX_NR_ZONES which is
|
||
* not a valid index then either kswapd runs for first time or kswapd couldn't
|
||
* sleep after previous reclaim attempt (node is still unbalanced). In that
|
||
* case return the zone index of the previous kswapd reclaim cycle.
|
||
*/
|
||
static enum zone_type kswapd_highest_zoneidx(pg_data_t *pgdat,
|
||
enum zone_type prev_highest_zoneidx)
|
||
{
|
||
enum zone_type curr_idx = READ_ONCE(pgdat->kswapd_highest_zoneidx);
|
||
|
||
return curr_idx == MAX_NR_ZONES ? prev_highest_zoneidx : curr_idx;
|
||
}
|
||
|
||
static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order,
|
||
unsigned int highest_zoneidx)
|
||
{
|
||
long remaining = 0;
|
||
DEFINE_WAIT(wait);
|
||
|
||
if (freezing(current) || kthread_should_stop())
|
||
return;
|
||
|
||
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
|
||
|
||
/*
|
||
* Try to sleep for a short interval. Note that kcompactd will only be
|
||
* woken if it is possible to sleep for a short interval. This is
|
||
* deliberate on the assumption that if reclaim cannot keep an
|
||
* eligible zone balanced that it's also unlikely that compaction will
|
||
* succeed.
|
||
*/
|
||
if (prepare_kswapd_sleep(pgdat, reclaim_order, highest_zoneidx)) {
|
||
/*
|
||
* Compaction records what page blocks it recently failed to
|
||
* isolate pages from and skips them in the future scanning.
|
||
* When kswapd is going to sleep, it is reasonable to assume
|
||
* that pages and compaction may succeed so reset the cache.
|
||
*/
|
||
reset_isolation_suitable(pgdat);
|
||
|
||
/*
|
||
* We have freed the memory, now we should compact it to make
|
||
* allocation of the requested order possible.
|
||
*/
|
||
wakeup_kcompactd(pgdat, alloc_order, highest_zoneidx);
|
||
|
||
remaining = schedule_timeout(HZ/10);
|
||
|
||
/*
|
||
* If woken prematurely then reset kswapd_highest_zoneidx and
|
||
* order. The values will either be from a wakeup request or
|
||
* the previous request that slept prematurely.
|
||
*/
|
||
if (remaining) {
|
||
WRITE_ONCE(pgdat->kswapd_highest_zoneidx,
|
||
kswapd_highest_zoneidx(pgdat,
|
||
highest_zoneidx));
|
||
|
||
if (READ_ONCE(pgdat->kswapd_order) < reclaim_order)
|
||
WRITE_ONCE(pgdat->kswapd_order, reclaim_order);
|
||
}
|
||
|
||
finish_wait(&pgdat->kswapd_wait, &wait);
|
||
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
|
||
}
|
||
|
||
/*
|
||
* After a short sleep, check if it was a premature sleep. If not, then
|
||
* go fully to sleep until explicitly woken up.
|
||
*/
|
||
if (!remaining &&
|
||
prepare_kswapd_sleep(pgdat, reclaim_order, highest_zoneidx)) {
|
||
trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
|
||
|
||
/*
|
||
* vmstat counters are not perfectly accurate and the estimated
|
||
* value for counters such as NR_FREE_PAGES can deviate from the
|
||
* true value by nr_online_cpus * threshold. To avoid the zone
|
||
* watermarks being breached while under pressure, we reduce the
|
||
* per-cpu vmstat threshold while kswapd is awake and restore
|
||
* them before going back to sleep.
|
||
*/
|
||
set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
|
||
|
||
if (!kthread_should_stop())
|
||
schedule();
|
||
|
||
set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
|
||
} else {
|
||
if (remaining)
|
||
count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
|
||
else
|
||
count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
|
||
}
|
||
finish_wait(&pgdat->kswapd_wait, &wait);
|
||
}
|
||
|
||
/*
|
||
* The background pageout daemon, started as a kernel thread
|
||
* from the init process.
|
||
*
|
||
* This basically trickles out pages so that we have _some_
|
||
* free memory available even if there is no other activity
|
||
* that frees anything up. This is needed for things like routing
|
||
* etc, where we otherwise might have all activity going on in
|
||
* asynchronous contexts that cannot page things out.
|
||
*
|
||
* If there are applications that are active memory-allocators
|
||
* (most normal use), this basically shouldn't matter.
|
||
*/
|
||
static int kswapd(void *p)
|
||
{
|
||
unsigned int alloc_order, reclaim_order;
|
||
unsigned int highest_zoneidx = MAX_NR_ZONES - 1;
|
||
pg_data_t *pgdat = (pg_data_t *)p;
|
||
struct task_struct *tsk = current;
|
||
const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
|
||
|
||
if (!cpumask_empty(cpumask))
|
||
set_cpus_allowed_ptr(tsk, cpumask);
|
||
|
||
/*
|
||
* Tell the memory management that we're a "memory allocator",
|
||
* and that if we need more memory we should get access to it
|
||
* regardless (see "__alloc_pages()"). "kswapd" should
|
||
* never get caught in the normal page freeing logic.
|
||
*
|
||
* (Kswapd normally doesn't need memory anyway, but sometimes
|
||
* you need a small amount of memory in order to be able to
|
||
* page out something else, and this flag essentially protects
|
||
* us from recursively trying to free more memory as we're
|
||
* trying to free the first piece of memory in the first place).
|
||
*/
|
||
tsk->flags |= PF_MEMALLOC | PF_KSWAPD;
|
||
set_freezable();
|
||
|
||
WRITE_ONCE(pgdat->kswapd_order, 0);
|
||
WRITE_ONCE(pgdat->kswapd_highest_zoneidx, MAX_NR_ZONES);
|
||
atomic_set(&pgdat->nr_writeback_throttled, 0);
|
||
for ( ; ; ) {
|
||
bool was_frozen;
|
||
|
||
alloc_order = reclaim_order = READ_ONCE(pgdat->kswapd_order);
|
||
highest_zoneidx = kswapd_highest_zoneidx(pgdat,
|
||
highest_zoneidx);
|
||
|
||
kswapd_try_sleep:
|
||
kswapd_try_to_sleep(pgdat, alloc_order, reclaim_order,
|
||
highest_zoneidx);
|
||
|
||
/* Read the new order and highest_zoneidx */
|
||
alloc_order = READ_ONCE(pgdat->kswapd_order);
|
||
highest_zoneidx = kswapd_highest_zoneidx(pgdat,
|
||
highest_zoneidx);
|
||
WRITE_ONCE(pgdat->kswapd_order, 0);
|
||
WRITE_ONCE(pgdat->kswapd_highest_zoneidx, MAX_NR_ZONES);
|
||
|
||
if (kthread_freezable_should_stop(&was_frozen))
|
||
break;
|
||
|
||
/*
|
||
* We can speed up thawing tasks if we don't call balance_pgdat
|
||
* after returning from the refrigerator
|
||
*/
|
||
if (was_frozen)
|
||
continue;
|
||
|
||
/*
|
||
* Reclaim begins at the requested order but if a high-order
|
||
* reclaim fails then kswapd falls back to reclaiming for
|
||
* order-0. If that happens, kswapd will consider sleeping
|
||
* for the order it finished reclaiming at (reclaim_order)
|
||
* but kcompactd is woken to compact for the original
|
||
* request (alloc_order).
|
||
*/
|
||
trace_mm_vmscan_kswapd_wake(pgdat->node_id, highest_zoneidx,
|
||
alloc_order);
|
||
reclaim_order = balance_pgdat(pgdat, alloc_order,
|
||
highest_zoneidx);
|
||
if (reclaim_order < alloc_order)
|
||
goto kswapd_try_sleep;
|
||
}
|
||
|
||
tsk->flags &= ~(PF_MEMALLOC | PF_KSWAPD);
|
||
|
||
return 0;
|
||
}
|
||
|
||
/*
|
||
* A zone is low on free memory or too fragmented for high-order memory. If
|
||
* kswapd should reclaim (direct reclaim is deferred), wake it up for the zone's
|
||
* pgdat. It will wake up kcompactd after reclaiming memory. If kswapd reclaim
|
||
* has failed or is not needed, still wake up kcompactd if only compaction is
|
||
* needed.
|
||
*/
|
||
void wakeup_kswapd(struct zone *zone, gfp_t gfp_flags, int order,
|
||
enum zone_type highest_zoneidx)
|
||
{
|
||
pg_data_t *pgdat;
|
||
enum zone_type curr_idx;
|
||
|
||
if (!managed_zone(zone))
|
||
return;
|
||
|
||
if (!cpuset_zone_allowed(zone, gfp_flags))
|
||
return;
|
||
|
||
pgdat = zone->zone_pgdat;
|
||
curr_idx = READ_ONCE(pgdat->kswapd_highest_zoneidx);
|
||
|
||
if (curr_idx == MAX_NR_ZONES || curr_idx < highest_zoneidx)
|
||
WRITE_ONCE(pgdat->kswapd_highest_zoneidx, highest_zoneidx);
|
||
|
||
if (READ_ONCE(pgdat->kswapd_order) < order)
|
||
WRITE_ONCE(pgdat->kswapd_order, order);
|
||
|
||
if (!waitqueue_active(&pgdat->kswapd_wait))
|
||
return;
|
||
|
||
/* Hopeless node, leave it to direct reclaim if possible */
|
||
if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES ||
|
||
(pgdat_balanced(pgdat, order, highest_zoneidx) &&
|
||
!pgdat_watermark_boosted(pgdat, highest_zoneidx))) {
|
||
/*
|
||
* There may be plenty of free memory available, but it's too
|
||
* fragmented for high-order allocations. Wake up kcompactd
|
||
* and rely on compaction_suitable() to determine if it's
|
||
* needed. If it fails, it will defer subsequent attempts to
|
||
* ratelimit its work.
|
||
*/
|
||
if (!(gfp_flags & __GFP_DIRECT_RECLAIM))
|
||
wakeup_kcompactd(pgdat, order, highest_zoneidx);
|
||
return;
|
||
}
|
||
|
||
trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, highest_zoneidx, order,
|
||
gfp_flags);
|
||
wake_up_interruptible(&pgdat->kswapd_wait);
|
||
}
|
||
|
||
#ifdef CONFIG_HIBERNATION
|
||
/*
|
||
* Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
|
||
* freed pages.
|
||
*
|
||
* Rather than trying to age LRUs the aim is to preserve the overall
|
||
* LRU order by reclaiming preferentially
|
||
* inactive > active > active referenced > active mapped
|
||
*/
|
||
unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
|
||
{
|
||
struct scan_control sc = {
|
||
.nr_to_reclaim = nr_to_reclaim,
|
||
.gfp_mask = GFP_HIGHUSER_MOVABLE,
|
||
.reclaim_idx = MAX_NR_ZONES - 1,
|
||
.priority = DEF_PRIORITY,
|
||
.may_writepage = 1,
|
||
.may_unmap = 1,
|
||
.may_swap = 1,
|
||
.hibernation_mode = 1,
|
||
};
|
||
struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
|
||
unsigned long nr_reclaimed;
|
||
unsigned int noreclaim_flag;
|
||
|
||
fs_reclaim_acquire(sc.gfp_mask);
|
||
noreclaim_flag = memalloc_noreclaim_save();
|
||
set_task_reclaim_state(current, &sc.reclaim_state);
|
||
|
||
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
|
||
|
||
set_task_reclaim_state(current, NULL);
|
||
memalloc_noreclaim_restore(noreclaim_flag);
|
||
fs_reclaim_release(sc.gfp_mask);
|
||
|
||
return nr_reclaimed;
|
||
}
|
||
#endif /* CONFIG_HIBERNATION */
|
||
|
||
/*
|
||
* This kswapd start function will be called by init and node-hot-add.
|
||
*/
|
||
void __meminit kswapd_run(int nid)
|
||
{
|
||
pg_data_t *pgdat = NODE_DATA(nid);
|
||
|
||
pgdat_kswapd_lock(pgdat);
|
||
if (!pgdat->kswapd) {
|
||
pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
|
||
if (IS_ERR(pgdat->kswapd)) {
|
||
/* failure at boot is fatal */
|
||
pr_err("Failed to start kswapd on node %d,ret=%ld\n",
|
||
nid, PTR_ERR(pgdat->kswapd));
|
||
BUG_ON(system_state < SYSTEM_RUNNING);
|
||
pgdat->kswapd = NULL;
|
||
}
|
||
}
|
||
pgdat_kswapd_unlock(pgdat);
|
||
}
|
||
|
||
/*
|
||
* Called by memory hotplug when all memory in a node is offlined. Caller must
|
||
* be holding mem_hotplug_begin/done().
|
||
*/
|
||
void __meminit kswapd_stop(int nid)
|
||
{
|
||
pg_data_t *pgdat = NODE_DATA(nid);
|
||
struct task_struct *kswapd;
|
||
|
||
pgdat_kswapd_lock(pgdat);
|
||
kswapd = pgdat->kswapd;
|
||
if (kswapd) {
|
||
kthread_stop(kswapd);
|
||
pgdat->kswapd = NULL;
|
||
}
|
||
pgdat_kswapd_unlock(pgdat);
|
||
}
|
||
|
||
static int __init kswapd_init(void)
|
||
{
|
||
int nid;
|
||
|
||
swap_setup();
|
||
for_each_node_state(nid, N_MEMORY)
|
||
kswapd_run(nid);
|
||
return 0;
|
||
}
|
||
|
||
module_init(kswapd_init)
|
||
|
||
#ifdef CONFIG_NUMA
|
||
/*
|
||
* Node reclaim mode
|
||
*
|
||
* If non-zero call node_reclaim when the number of free pages falls below
|
||
* the watermarks.
|
||
*/
|
||
int node_reclaim_mode __read_mostly;
|
||
|
||
/*
|
||
* Priority for NODE_RECLAIM. This determines the fraction of pages
|
||
* of a node considered for each zone_reclaim. 4 scans 1/16th of
|
||
* a zone.
|
||
*/
|
||
#define NODE_RECLAIM_PRIORITY 4
|
||
|
||
/*
|
||
* Percentage of pages in a zone that must be unmapped for node_reclaim to
|
||
* occur.
|
||
*/
|
||
int sysctl_min_unmapped_ratio = 1;
|
||
|
||
/*
|
||
* If the number of slab pages in a zone grows beyond this percentage then
|
||
* slab reclaim needs to occur.
|
||
*/
|
||
int sysctl_min_slab_ratio = 5;
|
||
|
||
static inline unsigned long node_unmapped_file_pages(struct pglist_data *pgdat)
|
||
{
|
||
unsigned long file_mapped = node_page_state(pgdat, NR_FILE_MAPPED);
|
||
unsigned long file_lru = node_page_state(pgdat, NR_INACTIVE_FILE) +
|
||
node_page_state(pgdat, NR_ACTIVE_FILE);
|
||
|
||
/*
|
||
* It's possible for there to be more file mapped pages than
|
||
* accounted for by the pages on the file LRU lists because
|
||
* tmpfs pages accounted for as ANON can also be FILE_MAPPED
|
||
*/
|
||
return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0;
|
||
}
|
||
|
||
/* Work out how many page cache pages we can reclaim in this reclaim_mode */
|
||
static unsigned long node_pagecache_reclaimable(struct pglist_data *pgdat)
|
||
{
|
||
unsigned long nr_pagecache_reclaimable;
|
||
unsigned long delta = 0;
|
||
|
||
/*
|
||
* If RECLAIM_UNMAP is set, then all file pages are considered
|
||
* potentially reclaimable. Otherwise, we have to worry about
|
||
* pages like swapcache and node_unmapped_file_pages() provides
|
||
* a better estimate
|
||
*/
|
||
if (node_reclaim_mode & RECLAIM_UNMAP)
|
||
nr_pagecache_reclaimable = node_page_state(pgdat, NR_FILE_PAGES);
|
||
else
|
||
nr_pagecache_reclaimable = node_unmapped_file_pages(pgdat);
|
||
|
||
/* If we can't clean pages, remove dirty pages from consideration */
|
||
if (!(node_reclaim_mode & RECLAIM_WRITE))
|
||
delta += node_page_state(pgdat, NR_FILE_DIRTY);
|
||
|
||
/* Watch for any possible underflows due to delta */
|
||
if (unlikely(delta > nr_pagecache_reclaimable))
|
||
delta = nr_pagecache_reclaimable;
|
||
|
||
return nr_pagecache_reclaimable - delta;
|
||
}
|
||
|
||
/*
|
||
* Try to free up some pages from this node through reclaim.
|
||
*/
|
||
static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order)
|
||
{
|
||
/* Minimum pages needed in order to stay on node */
|
||
const unsigned long nr_pages = 1 << order;
|
||
struct task_struct *p = current;
|
||
unsigned int noreclaim_flag;
|
||
struct scan_control sc = {
|
||
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
|
||
.gfp_mask = current_gfp_context(gfp_mask),
|
||
.order = order,
|
||
.priority = NODE_RECLAIM_PRIORITY,
|
||
.may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE),
|
||
.may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP),
|
||
.may_swap = 1,
|
||
.reclaim_idx = gfp_zone(gfp_mask),
|
||
};
|
||
unsigned long pflags;
|
||
|
||
trace_mm_vmscan_node_reclaim_begin(pgdat->node_id, order,
|
||
sc.gfp_mask);
|
||
|
||
cond_resched();
|
||
psi_memstall_enter(&pflags);
|
||
delayacct_freepages_start();
|
||
fs_reclaim_acquire(sc.gfp_mask);
|
||
/*
|
||
* We need to be able to allocate from the reserves for RECLAIM_UNMAP
|
||
*/
|
||
noreclaim_flag = memalloc_noreclaim_save();
|
||
set_task_reclaim_state(p, &sc.reclaim_state);
|
||
|
||
if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages ||
|
||
node_page_state_pages(pgdat, NR_SLAB_RECLAIMABLE_B) > pgdat->min_slab_pages) {
|
||
/*
|
||
* Free memory by calling shrink node with increasing
|
||
* priorities until we have enough memory freed.
|
||
*/
|
||
do {
|
||
shrink_node(pgdat, &sc);
|
||
} while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0);
|
||
}
|
||
|
||
set_task_reclaim_state(p, NULL);
|
||
memalloc_noreclaim_restore(noreclaim_flag);
|
||
fs_reclaim_release(sc.gfp_mask);
|
||
psi_memstall_leave(&pflags);
|
||
delayacct_freepages_end();
|
||
|
||
trace_mm_vmscan_node_reclaim_end(sc.nr_reclaimed);
|
||
|
||
return sc.nr_reclaimed >= nr_pages;
|
||
}
|
||
|
||
int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order)
|
||
{
|
||
int ret;
|
||
|
||
/*
|
||
* Node reclaim reclaims unmapped file backed pages and
|
||
* slab pages if we are over the defined limits.
|
||
*
|
||
* A small portion of unmapped file backed pages is needed for
|
||
* file I/O otherwise pages read by file I/O will be immediately
|
||
* thrown out if the node is overallocated. So we do not reclaim
|
||
* if less than a specified percentage of the node is used by
|
||
* unmapped file backed pages.
|
||
*/
|
||
if (node_pagecache_reclaimable(pgdat) <= pgdat->min_unmapped_pages &&
|
||
node_page_state_pages(pgdat, NR_SLAB_RECLAIMABLE_B) <=
|
||
pgdat->min_slab_pages)
|
||
return NODE_RECLAIM_FULL;
|
||
|
||
/*
|
||
* Do not scan if the allocation should not be delayed.
|
||
*/
|
||
if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC))
|
||
return NODE_RECLAIM_NOSCAN;
|
||
|
||
/*
|
||
* Only run node reclaim on the local node or on nodes that do not
|
||
* have associated processors. This will favor the local processor
|
||
* over remote processors and spread off node memory allocations
|
||
* as wide as possible.
|
||
*/
|
||
if (node_state(pgdat->node_id, N_CPU) && pgdat->node_id != numa_node_id())
|
||
return NODE_RECLAIM_NOSCAN;
|
||
|
||
if (test_and_set_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags))
|
||
return NODE_RECLAIM_NOSCAN;
|
||
|
||
ret = __node_reclaim(pgdat, gfp_mask, order);
|
||
clear_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags);
|
||
|
||
if (ret)
|
||
count_vm_event(PGSCAN_ZONE_RECLAIM_SUCCESS);
|
||
else
|
||
count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED);
|
||
|
||
return ret;
|
||
}
|
||
#endif
|
||
|
||
/**
|
||
* check_move_unevictable_folios - Move evictable folios to appropriate zone
|
||
* lru list
|
||
* @fbatch: Batch of lru folios to check.
|
||
*
|
||
* Checks folios for evictability, if an evictable folio is in the unevictable
|
||
* lru list, moves it to the appropriate evictable lru list. This function
|
||
* should be only used for lru folios.
|
||
*/
|
||
void check_move_unevictable_folios(struct folio_batch *fbatch)
|
||
{
|
||
struct lruvec *lruvec = NULL;
|
||
int pgscanned = 0;
|
||
int pgrescued = 0;
|
||
int i;
|
||
|
||
for (i = 0; i < fbatch->nr; i++) {
|
||
struct folio *folio = fbatch->folios[i];
|
||
int nr_pages = folio_nr_pages(folio);
|
||
|
||
pgscanned += nr_pages;
|
||
|
||
/* block memcg migration while the folio moves between lrus */
|
||
if (!folio_test_clear_lru(folio))
|
||
continue;
|
||
|
||
lruvec = folio_lruvec_relock_irq(folio, lruvec);
|
||
if (folio_evictable(folio) && folio_test_unevictable(folio)) {
|
||
lruvec_del_folio(lruvec, folio);
|
||
folio_clear_unevictable(folio);
|
||
lruvec_add_folio(lruvec, folio);
|
||
pgrescued += nr_pages;
|
||
}
|
||
folio_set_lru(folio);
|
||
}
|
||
|
||
if (lruvec) {
|
||
__count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
|
||
__count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned);
|
||
unlock_page_lruvec_irq(lruvec);
|
||
} else if (pgscanned) {
|
||
count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned);
|
||
}
|
||
}
|
||
EXPORT_SYMBOL_GPL(check_move_unevictable_folios);
|