mm: swap: add nr argument in swapcache_prepare and swapcache_clear to support large folios
Right now, swapcache_prepare() and swapcache_clear() supports one entry only, to support large folios, we need to handle multiple swap entries. To optimize stack usage, we iterate twice in __swap_duplicate(): the first time to verify that all entries are valid, and the second time to apply the modifications to the entries. Currently, we're using nr=1 for the existing users. [v-songbaohua@oppo.com: clarify swap_count_continued and improve readability for __swap_duplicate] Link: https://lkml.kernel.org/r/20240802071817.47081-1-21cnbao@gmail.com Link: https://lkml.kernel.org/r/20240730071339.107447-2-21cnbao@gmail.com Signed-off-by: Barry Song <v-songbaohua@oppo.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Acked-by: David Hildenbrand <david@redhat.com> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Chris Li <chrisl@kernel.org> Cc: Gao Xiang <xiang@kernel.org> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kairui Song <kasong@tencent.com> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Shakeel Butt <shakeel.butt@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Yosry Ahmed <yosryahmed@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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7e60dcb222
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9f101bef40
@ -480,7 +480,7 @@ extern int get_swap_pages(int n, swp_entry_t swp_entries[], int order);
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extern int add_swap_count_continuation(swp_entry_t, gfp_t);
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extern int add_swap_count_continuation(swp_entry_t, gfp_t);
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extern void swap_shmem_alloc(swp_entry_t);
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extern void swap_shmem_alloc(swp_entry_t);
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extern int swap_duplicate(swp_entry_t);
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extern int swap_duplicate(swp_entry_t);
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extern int swapcache_prepare(swp_entry_t);
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extern int swapcache_prepare(swp_entry_t entry, int nr);
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extern void swap_free_nr(swp_entry_t entry, int nr_pages);
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extern void swap_free_nr(swp_entry_t entry, int nr_pages);
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extern void swapcache_free_entries(swp_entry_t *entries, int n);
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extern void swapcache_free_entries(swp_entry_t *entries, int n);
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extern void free_swap_and_cache_nr(swp_entry_t entry, int nr);
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extern void free_swap_and_cache_nr(swp_entry_t entry, int nr);
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@ -554,7 +554,7 @@ static inline int swap_duplicate(swp_entry_t swp)
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return 0;
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return 0;
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}
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}
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static inline int swapcache_prepare(swp_entry_t swp)
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static inline int swapcache_prepare(swp_entry_t swp, int nr)
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{
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{
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return 0;
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return 0;
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}
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}
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@ -4081,7 +4081,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
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* reusing the same entry. It's undetectable as
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* reusing the same entry. It's undetectable as
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* pte_same() returns true due to entry reuse.
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* pte_same() returns true due to entry reuse.
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*/
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*/
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if (swapcache_prepare(entry)) {
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if (swapcache_prepare(entry, 1)) {
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/* Relax a bit to prevent rapid repeated page faults */
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/* Relax a bit to prevent rapid repeated page faults */
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schedule_timeout_uninterruptible(1);
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schedule_timeout_uninterruptible(1);
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goto out;
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goto out;
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@ -4387,7 +4387,7 @@ unlock:
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out:
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out:
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/* Clear the swap cache pin for direct swapin after PTL unlock */
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/* Clear the swap cache pin for direct swapin after PTL unlock */
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if (need_clear_cache)
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if (need_clear_cache)
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swapcache_clear(si, entry);
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swapcache_clear(si, entry, 1);
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if (si)
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if (si)
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put_swap_device(si);
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put_swap_device(si);
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return ret;
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return ret;
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@ -4403,7 +4403,7 @@ out_release:
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folio_put(swapcache);
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folio_put(swapcache);
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}
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}
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if (need_clear_cache)
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if (need_clear_cache)
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swapcache_clear(si, entry);
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swapcache_clear(si, entry, 1);
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if (si)
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if (si)
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put_swap_device(si);
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put_swap_device(si);
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return ret;
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return ret;
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@ -59,7 +59,7 @@ void __delete_from_swap_cache(struct folio *folio,
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void delete_from_swap_cache(struct folio *folio);
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void delete_from_swap_cache(struct folio *folio);
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void clear_shadow_from_swap_cache(int type, unsigned long begin,
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void clear_shadow_from_swap_cache(int type, unsigned long begin,
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unsigned long end);
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unsigned long end);
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void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry);
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void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr);
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struct folio *swap_cache_get_folio(swp_entry_t entry,
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struct folio *swap_cache_get_folio(swp_entry_t entry,
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struct vm_area_struct *vma, unsigned long addr);
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struct vm_area_struct *vma, unsigned long addr);
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struct folio *filemap_get_incore_folio(struct address_space *mapping,
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struct folio *filemap_get_incore_folio(struct address_space *mapping,
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@ -120,7 +120,7 @@ static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
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return 0;
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return 0;
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}
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}
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static inline void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry)
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static inline void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr)
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{
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{
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}
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}
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@ -172,4 +172,5 @@ static inline unsigned int folio_swap_flags(struct folio *folio)
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return 0;
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return 0;
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}
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}
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#endif /* CONFIG_SWAP */
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#endif /* CONFIG_SWAP */
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#endif /* _MM_SWAP_H */
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#endif /* _MM_SWAP_H */
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@ -477,7 +477,7 @@ struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
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/*
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/*
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* Swap entry may have been freed since our caller observed it.
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* Swap entry may have been freed since our caller observed it.
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*/
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*/
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err = swapcache_prepare(entry);
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err = swapcache_prepare(entry, 1);
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if (!err)
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if (!err)
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break;
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break;
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@ -3363,7 +3363,7 @@ void si_swapinfo(struct sysinfo *val)
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}
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}
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/*
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/*
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* Verify that a swap entry is valid and increment its swap map count.
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* Verify that nr swap entries are valid and increment their swap map counts.
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*
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*
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* Returns error code in following case.
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* Returns error code in following case.
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* - success -> 0
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* - success -> 0
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@ -3373,60 +3373,73 @@ void si_swapinfo(struct sysinfo *val)
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* - swap-cache reference is requested but the entry is not used. -> ENOENT
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* - swap-cache reference is requested but the entry is not used. -> ENOENT
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* - swap-mapped reference requested but needs continued swap count. -> ENOMEM
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* - swap-mapped reference requested but needs continued swap count. -> ENOMEM
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*/
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*/
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static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
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static int __swap_duplicate(swp_entry_t entry, unsigned char usage, int nr)
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{
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{
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struct swap_info_struct *p;
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struct swap_info_struct *p;
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struct swap_cluster_info *ci;
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struct swap_cluster_info *ci;
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unsigned long offset;
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unsigned long offset;
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unsigned char count;
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unsigned char count;
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unsigned char has_cache;
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unsigned char has_cache;
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int err;
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int err, i;
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p = swp_swap_info(entry);
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p = swp_swap_info(entry);
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offset = swp_offset(entry);
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offset = swp_offset(entry);
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VM_WARN_ON(nr > SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER);
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VM_WARN_ON(usage == 1 && nr > 1);
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ci = lock_cluster_or_swap_info(p, offset);
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ci = lock_cluster_or_swap_info(p, offset);
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count = p->swap_map[offset];
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err = 0;
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for (i = 0; i < nr; i++) {
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count = p->swap_map[offset + i];
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/*
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/*
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* swapin_readahead() doesn't check if a swap entry is valid, so the
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* swapin_readahead() doesn't check if a swap entry is valid, so the
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* swap entry could be SWAP_MAP_BAD. Check here with lock held.
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* swap entry could be SWAP_MAP_BAD. Check here with lock held.
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*/
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*/
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if (unlikely(swap_count(count) == SWAP_MAP_BAD)) {
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if (unlikely(swap_count(count) == SWAP_MAP_BAD)) {
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err = -ENOENT;
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err = -ENOENT;
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goto unlock_out;
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goto unlock_out;
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}
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has_cache = count & SWAP_HAS_CACHE;
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count &= ~SWAP_HAS_CACHE;
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if (!count && !has_cache) {
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err = -ENOENT;
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} else if (usage == SWAP_HAS_CACHE) {
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if (has_cache)
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err = -EEXIST;
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} else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) {
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err = -EINVAL;
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}
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if (err)
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goto unlock_out;
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}
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}
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has_cache = count & SWAP_HAS_CACHE;
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for (i = 0; i < nr; i++) {
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count &= ~SWAP_HAS_CACHE;
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count = p->swap_map[offset + i];
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err = 0;
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has_cache = count & SWAP_HAS_CACHE;
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count &= ~SWAP_HAS_CACHE;
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if (usage == SWAP_HAS_CACHE) {
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if (usage == SWAP_HAS_CACHE)
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/* set SWAP_HAS_CACHE if there is no cache and entry is used */
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if (!has_cache && count)
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has_cache = SWAP_HAS_CACHE;
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has_cache = SWAP_HAS_CACHE;
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else if (has_cache) /* someone else added cache */
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else if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX)
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err = -EEXIST;
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else /* no users remaining */
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err = -ENOENT;
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} else if (count || has_cache) {
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if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX)
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count += usage;
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count += usage;
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else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX)
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else if (swap_count_continued(p, offset + i, count))
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err = -EINVAL;
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else if (swap_count_continued(p, offset, count))
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count = COUNT_CONTINUED;
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count = COUNT_CONTINUED;
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else
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else {
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/*
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* Don't need to rollback changes, because if
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* usage == 1, there must be nr == 1.
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*/
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err = -ENOMEM;
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err = -ENOMEM;
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} else
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goto unlock_out;
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err = -ENOENT; /* unused swap entry */
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}
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if (!err)
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WRITE_ONCE(p->swap_map[offset + i], count | has_cache);
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WRITE_ONCE(p->swap_map[offset], count | has_cache);
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}
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unlock_out:
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unlock_out:
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unlock_cluster_or_swap_info(p, ci);
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unlock_cluster_or_swap_info(p, ci);
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@ -3439,7 +3452,7 @@ unlock_out:
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*/
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*/
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void swap_shmem_alloc(swp_entry_t entry)
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void swap_shmem_alloc(swp_entry_t entry)
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{
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{
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__swap_duplicate(entry, SWAP_MAP_SHMEM);
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__swap_duplicate(entry, SWAP_MAP_SHMEM, 1);
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}
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}
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/*
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/*
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@ -3453,29 +3466,29 @@ int swap_duplicate(swp_entry_t entry)
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{
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{
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int err = 0;
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int err = 0;
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while (!err && __swap_duplicate(entry, 1) == -ENOMEM)
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while (!err && __swap_duplicate(entry, 1, 1) == -ENOMEM)
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err = add_swap_count_continuation(entry, GFP_ATOMIC);
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err = add_swap_count_continuation(entry, GFP_ATOMIC);
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return err;
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return err;
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}
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}
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/*
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/*
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* @entry: swap entry for which we allocate swap cache.
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* @entry: first swap entry from which we allocate nr swap cache.
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*
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*
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* Called when allocating swap cache for existing swap entry,
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* Called when allocating swap cache for existing swap entries,
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* This can return error codes. Returns 0 at success.
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* This can return error codes. Returns 0 at success.
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* -EEXIST means there is a swap cache.
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* -EEXIST means there is a swap cache.
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* Note: return code is different from swap_duplicate().
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* Note: return code is different from swap_duplicate().
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*/
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*/
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int swapcache_prepare(swp_entry_t entry)
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int swapcache_prepare(swp_entry_t entry, int nr)
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{
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{
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return __swap_duplicate(entry, SWAP_HAS_CACHE);
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return __swap_duplicate(entry, SWAP_HAS_CACHE, nr);
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}
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}
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void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry)
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void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr)
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{
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{
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unsigned long offset = swp_offset(entry);
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unsigned long offset = swp_offset(entry);
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cluster_swap_free_nr(si, offset, 1, SWAP_HAS_CACHE);
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cluster_swap_free_nr(si, offset, nr, SWAP_HAS_CACHE);
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}
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}
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struct swap_info_struct *swp_swap_info(swp_entry_t entry)
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struct swap_info_struct *swp_swap_info(swp_entry_t entry)
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