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bc56620b49
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Hugh Dickins bc56620b49 ksm: shrink 32-bit rmap_item back to 32 bytes 
Think of struct rmap_item as an extension of struct page (restricted to
MADV_MERGEABLE areas): there may be a lot of them, we need to keep them
small, especially on 32-bit architectures of limited lowmem.

Siting "int nid" after "unsigned int checksum" works nicely on 64-bit,
making no change to its 64-byte struct rmap_item; but bloats the 32-bit
struct rmap_item from (nicely cache-aligned) 32 bytes to 36 bytes, which
rounds up to 40 bytes once allocated from slab.  We'd better avoid that.

Hey, I only just remembered that the anon_vma pointer in struct
rmap_item has no purpose until the rmap_item is hung from a stable tree
node (which has its own nid field); and rmap_item's nid field no purpose
than to say which tree root to tell rb_erase() when unlinking from an
unstable tree.

Double them up in a union.  There's just one place where we set anon_vma
early (when we already hold mmap_sem): now we must remove tree_rmap_item
from its unstable tree there, before overwriting nid.  No need to
spatter BUG()s around: we'd be seeing oopses if this were wrong.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Petr Holasek <pholasek@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Izik Eidus <izik.eidus@ravellosystems.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-23 17:50:23 -08:00
..
backing-dev.c bdi: allow block devices to say that they require stable page writes 2013-02-21 17:22:19 -08:00
balloon_compaction.c mm: introduce a common interface for balloon pages mobility 2012-12-11 17:22:26 -08:00
bootmem.c mm: Add alloc_bootmem_low_pages_nopanic() 2013-01-29 19:32:59 -08:00
bounce.c block: optionally snapshot page contents to provide stable pages during write 2013-02-21 17:22:20 -08:00
cleancache.c ->encode_fh() API change 2012-05-29 23:28:33 -04:00
compaction.c mm: add & use zone_end_pfn() and zone_spans_pfn() 2013-02-23 17:50:20 -08:00
debug-pagealloc.c
dmapool.c dmapool: make DMAPOOL_DEBUG detect corruption of free marker 2012-12-11 17:22:24 -08:00
fadvise.c mm/fadvise.c: drain all pagevecs if POSIX_FADV_DONTNEED fails to discard all pages 2013-02-23 17:50:23 -08:00
failslab.c
filemap_xip.c mm: move all mmu notifier invocations to be done outside the PT lock 2012-10-09 16:22:58 +09:00
filemap.c mm: only enforce stable page writes if the backing device requires it 2013-02-21 17:22:19 -08:00
fremap.c mm: introduce VM_POPULATE flag to better deal with racy userspace programs 2013-02-23 17:50:11 -08:00
frontswap.c frontswap: support exclusive gets if tmem backend is capable 2012-09-21 10:38:12 -04:00
highmem.c Some nice cleanups, and even a patch my wife did as a "live" demo for 2012-12-20 08:37:05 -08:00
huge_memory.c mm: use NUMA_NO_NODE 2013-02-23 17:50:21 -08:00
hugetlb_cgroup.c mm/hugetlb: create hugetlb cgroup file in hugetlb_init 2012-12-18 15:02:15 -08:00
hugetlb.c mm: use long type for page counts in mm_populate() and get_user_pages() 2013-02-23 17:50:22 -08:00
hwpoison-inject.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
init-mm.c
internal.h mm: directly use __mlock_vma_pages_range() in find_extend_vma() 2013-02-23 17:50:11 -08:00
interval_tree.c mm: add CONFIG_DEBUG_VM_RB build option 2012-10-09 16:22:42 +09:00
Kconfig memory-hotplug: implement register_page_bootmem_info_section of sparse-vmemmap 2013-02-23 17:50:12 -08:00
Kconfig.debug
kmemcheck.c
kmemleak-test.c
kmemleak.c mm: add & use zone_end_pfn() and zone_spans_pfn() 2013-02-23 17:50:20 -08:00
ksm.c ksm: shrink 32-bit rmap_item back to 32 bytes 2013-02-23 17:50:23 -08:00
maccess.c
madvise.c mm: make madvise(MADV_WILLNEED) support swap file prefetch 2013-02-23 17:50:10 -08:00
Makefile mm: introduce a common interface for balloon pages mobility 2012-12-11 17:22:26 -08:00
memblock.c mm/memblock.c: use CONFIG_HAVE_MEMBLOCK_NODE_MAP to protect movablecore_map in memblock_overlaps_region(). 2013-02-23 17:50:14 -08:00
memcontrol.c memcg: stop warning on memcg_propagate_kmem 2013-02-23 17:50:22 -08:00
memory_hotplug.c mm/memory_hotplug: use pgdat_end_pfn() instead of open coding the same. 2013-02-23 17:50:21 -08:00
memory-failure.c HWPOISON: change order of error_states[]'s elements 2013-02-23 17:50:22 -08:00
memory.c mm: accelerate mm_populate() treatment of THP pages 2013-02-23 17:50:23 -08:00
mempolicy.c mm: use NUMA_NO_NODE 2013-02-23 17:50:21 -08:00
mempool.c mempool: add @gfp_mask to mempool_create_node() 2012-06-25 11:53:47 +02:00
migrate.c mm: remove offlining arg to migrate_pages 2013-02-23 17:50:19 -08:00
mincore.c swap: make each swap partition have one address_space 2013-02-23 17:50:17 -08:00
mlock.c mm: use long type for page counts in mm_populate() and get_user_pages() 2013-02-23 17:50:22 -08:00
mm_init.c mm: init: report on last-nid information stored in page->flags 2013-02-23 17:50:18 -08:00
mmap.c mm/rmap: rename anon_vma_unlock() => anon_vma_unlock_write() 2013-02-23 17:50:17 -08:00
mmu_context.c mm, counters: remove task argument to sync_mm_rss() and __sync_task_rss_stat() 2012-03-21 17:54:59 -07:00
mmu_notifier.c mm: export mmu notifier invalidates 2013-02-23 17:50:23 -08:00
mmzone.c mm: rename page struct field helpers 2013-02-23 17:50:18 -08:00
mprotect.c mm/mprotect.c: coding-style cleanups 2012-12-18 15:02:15 -08:00
mremap.c mm/rmap: rename anon_vma_unlock() => anon_vma_unlock_write() 2013-02-23 17:50:17 -08:00
msync.c
nobootmem.c mm: Add alloc_bootmem_low_pages_nopanic() 2013-01-29 19:32:59 -08:00
nommu.c mm: accelerate mm_populate() treatment of THP pages 2013-02-23 17:50:23 -08:00
oom_kill.c memcg, oom: provide more precise dump info while memcg oom happening 2013-02-23 17:50:08 -08:00
page_alloc.c mm: accurately document nr_free_*_pages functions with code comments 2013-02-23 17:50:22 -08:00
page_cgroup.c memcontrol: use N_MEMORY instead N_HIGH_MEMORY 2012-12-12 17:38:32 -08:00
page_io.c mm: add support for direct_IO to highmem pages 2012-07-31 18:42:47 -07:00
page_isolation.c mm: fix zone_watermark_ok_safe() accounting of isolated pages 2013-01-04 16:11:46 -08:00
page-writeback.c page-writeback.c: subtract min_free_kbytes from dirtyable memory 2013-02-23 17:50:17 -08:00
pagewalk.c thp: change split_huge_page_pmd() interface 2012-12-12 17:38:31 -08:00
percpu-km.c
percpu-vm.c mm: fix kernel-doc warnings 2012-06-20 14:39:36 -07:00
percpu.c mm, percpu: Make sure percpu_alloc early parameter has an argument 2012-12-02 06:23:04 -08:00
pgtable-generic.c mm: Only flush the TLB when clearing an accessible pte 2012-12-11 14:28:34 +00:00
process_vm_access.c aio/vfs: cleanup of rw_copy_check_uvector() and compat_rw_copy_check_uvector() 2012-05-31 17:49:32 -07:00
quicklist.c
readahead.c switch simple cases of fget_light to fdget 2012-09-26 22:20:08 -04:00
rmap.c mm/rmap: rename anon_vma_unlock() => anon_vma_unlock_write() 2013-02-23 17:50:17 -08:00
shmem.c tmpfs: fix mempolicy object leaks 2013-02-23 17:50:23 -08:00
slab_common.c slab: propagate tunable values 2012-12-18 15:02:14 -08:00
slab.c memcg: add comments clarifying aspects of cache attribute propagation 2012-12-18 15:02:15 -08:00
slab.h slab: propagate tunable values 2012-12-18 15:02:14 -08:00
slob.c mm: rename page struct field helpers 2013-02-23 17:50:18 -08:00
slub.c mm: rename page struct field helpers 2013-02-23 17:50:18 -08:00
sparse-vmemmap.c
sparse.c memory-failure: use num_poisoned_pages instead of mce_bad_pages 2013-02-23 17:50:15 -08:00
swap_state.c swap: add per-partition lock for swapfile 2013-02-23 17:50:17 -08:00
swap.c swap: make each swap partition have one address_space 2013-02-23 17:50:17 -08:00
swapfile.c swap: add per-partition lock for swapfile 2013-02-23 17:50:17 -08:00
truncate.c mm: drop vmtruncate 2012-12-20 18:46:29 -05:00
util.c swap: make each swap partition have one address_space 2013-02-23 17:50:17 -08:00
vmalloc.c mm: use NUMA_NO_NODE 2013-02-23 17:50:21 -08:00
vmscan.c vmscan: change type of vm_total_pages to unsigned long 2013-02-23 17:50:22 -08:00
vmstat.c mm: add & use zone_end_pfn() and zone_spans_pfn() 2013-02-23 17:50:20 -08:00