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page-flags: define PG_locked behavior on compound pages
lock_page() must operate on the whole compound page. It doesn't make much sense to lock part of compound page. Change code to use head page's PG_locked, if tail page is passed. This patch also gets rid of custom helper functions -- __set_page_locked() and __clear_page_locked(). They are replaced with helpers generated by __SETPAGEFLAG/__CLEARPAGEFLAG. Tail pages to these helper would trigger VM_BUG_ON(). SLUB uses PG_locked as a bit spin locked. IIUC, tail pages should never appear there. VM_BUG_ON() is added to make sure that this assumption is correct. [akpm@linux-foundation.org: fix fs/cifs/file.c] Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -3391,13 +3391,13 @@ readpages_get_pages(struct address_space *mapping, struct list_head *page_list,
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* should have access to this page, we're safe to simply set
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* PG_locked without checking it first.
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*/
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__set_page_locked(page);
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__SetPageLocked(page);
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rc = add_to_page_cache_locked(page, mapping,
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page->index, gfp);
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/* give up if we can't stick it in the cache */
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if (rc) {
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__clear_page_locked(page);
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__ClearPageLocked(page);
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return rc;
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}
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@ -3418,9 +3418,9 @@ readpages_get_pages(struct address_space *mapping, struct list_head *page_list,
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if (*bytes + PAGE_CACHE_SIZE > rsize)
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break;
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__set_page_locked(page);
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__SetPageLocked(page);
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if (add_to_page_cache_locked(page, mapping, page->index, gfp)) {
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__clear_page_locked(page);
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__ClearPageLocked(page);
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break;
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}
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list_move_tail(&page->lru, tmplist);
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@ -256,7 +256,7 @@ static inline int __TestClearPage##uname(struct page *page) { return 0; }
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#define TESTSCFLAG_FALSE(uname) \
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TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
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TESTPAGEFLAG(Locked, locked, PF_ANY)
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__PAGEFLAG(Locked, locked, PF_NO_TAIL)
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PAGEFLAG(Error, error, PF_ANY) TESTCLEARFLAG(Error, error, PF_ANY)
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PAGEFLAG(Referenced, referenced, PF_ANY) TESTCLEARFLAG(Referenced, referenced, PF_ANY)
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__SETPAGEFLAG(Referenced, referenced, PF_ANY)
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@ -433,18 +433,9 @@ extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
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unsigned int flags);
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extern void unlock_page(struct page *page);
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static inline void __set_page_locked(struct page *page)
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{
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__set_bit(PG_locked, &page->flags);
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}
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static inline void __clear_page_locked(struct page *page)
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{
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__clear_bit(PG_locked, &page->flags);
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}
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static inline int trylock_page(struct page *page)
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{
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page = compound_head(page);
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return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
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}
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@ -497,9 +488,9 @@ extern int wait_on_page_bit_killable_timeout(struct page *page,
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static inline int wait_on_page_locked_killable(struct page *page)
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{
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if (PageLocked(page))
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return wait_on_page_bit_killable(page, PG_locked);
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return 0;
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if (!PageLocked(page))
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return 0;
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return wait_on_page_bit_killable(compound_head(page), PG_locked);
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}
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extern wait_queue_head_t *page_waitqueue(struct page *page);
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@ -518,7 +509,7 @@ static inline void wake_up_page(struct page *page, int bit)
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static inline void wait_on_page_locked(struct page *page)
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{
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if (PageLocked(page))
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wait_on_page_bit(page, PG_locked);
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wait_on_page_bit(compound_head(page), PG_locked);
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}
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/*
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@ -664,17 +655,17 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
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/*
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* Like add_to_page_cache_locked, but used to add newly allocated pages:
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* the page is new, so we can just run __set_page_locked() against it.
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* the page is new, so we can just run __SetPageLocked() against it.
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*/
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static inline int add_to_page_cache(struct page *page,
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struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
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{
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int error;
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__set_page_locked(page);
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__SetPageLocked(page);
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error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
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if (unlikely(error))
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__clear_page_locked(page);
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__ClearPageLocked(page);
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return error;
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}
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15
mm/filemap.c
15
mm/filemap.c
@ -682,11 +682,11 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
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void *shadow = NULL;
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int ret;
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__set_page_locked(page);
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__SetPageLocked(page);
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ret = __add_to_page_cache_locked(page, mapping, offset,
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gfp_mask, &shadow);
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if (unlikely(ret))
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__clear_page_locked(page);
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__ClearPageLocked(page);
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else {
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/*
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* The page might have been evicted from cache only
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@ -809,6 +809,7 @@ EXPORT_SYMBOL_GPL(add_page_wait_queue);
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*/
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void unlock_page(struct page *page)
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{
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page = compound_head(page);
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VM_BUG_ON_PAGE(!PageLocked(page), page);
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clear_bit_unlock(PG_locked, &page->flags);
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smp_mb__after_atomic();
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@ -873,18 +874,20 @@ EXPORT_SYMBOL_GPL(page_endio);
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*/
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void __lock_page(struct page *page)
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{
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DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
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struct page *page_head = compound_head(page);
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DEFINE_WAIT_BIT(wait, &page_head->flags, PG_locked);
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__wait_on_bit_lock(page_waitqueue(page), &wait, bit_wait_io,
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__wait_on_bit_lock(page_waitqueue(page_head), &wait, bit_wait_io,
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TASK_UNINTERRUPTIBLE);
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}
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EXPORT_SYMBOL(__lock_page);
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int __lock_page_killable(struct page *page)
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{
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DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
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struct page *page_head = compound_head(page);
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DEFINE_WAIT_BIT(wait, &page_head->flags, PG_locked);
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return __wait_on_bit_lock(page_waitqueue(page), &wait,
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return __wait_on_bit_lock(page_waitqueue(page_head), &wait,
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bit_wait_io, TASK_KILLABLE);
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}
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EXPORT_SYMBOL_GPL(__lock_page_killable);
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2
mm/ksm.c
2
mm/ksm.c
@ -1899,7 +1899,7 @@ struct page *ksm_might_need_to_copy(struct page *page,
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SetPageDirty(new_page);
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__SetPageUptodate(new_page);
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__set_page_locked(new_page);
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__SetPageLocked(new_page);
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}
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return new_page;
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@ -1166,7 +1166,7 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
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/*
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* We ignore non-LRU pages for good reasons.
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* - PG_locked is only well defined for LRU pages and a few others
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* - to avoid races with __set_page_locked()
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* - to avoid races with __SetPageLocked()
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* - to avoid races with __SetPageSlab*() (and more non-atomic ops)
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* The check (unnecessarily) ignores LRU pages being isolated and
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* walked by the page reclaim code, however that's not a big loss.
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@ -1767,7 +1767,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
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flush_tlb_range(vma, mmun_start, mmun_end);
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/* Prepare a page as a migration target */
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__set_page_locked(new_page);
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__SetPageLocked(new_page);
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SetPageSwapBacked(new_page);
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/* anon mapping, we can simply copy page->mapping to the new page: */
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@ -1085,7 +1085,7 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
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copy_highpage(newpage, oldpage);
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flush_dcache_page(newpage);
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__set_page_locked(newpage);
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__SetPageLocked(newpage);
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SetPageUptodate(newpage);
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SetPageSwapBacked(newpage);
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set_page_private(newpage, swap_index);
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@ -1277,7 +1277,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
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}
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__SetPageSwapBacked(page);
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__set_page_locked(page);
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__SetPageLocked(page);
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if (sgp == SGP_WRITE)
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__SetPageReferenced(page);
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@ -338,11 +338,13 @@ static inline int oo_objects(struct kmem_cache_order_objects x)
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*/
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static __always_inline void slab_lock(struct page *page)
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{
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VM_BUG_ON_PAGE(PageTail(page), page);
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bit_spin_lock(PG_locked, &page->flags);
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}
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static __always_inline void slab_unlock(struct page *page)
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{
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VM_BUG_ON_PAGE(PageTail(page), page);
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__bit_spin_unlock(PG_locked, &page->flags);
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}
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@ -353,7 +353,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
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}
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/* May fail (-ENOMEM) if radix-tree node allocation failed. */
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__set_page_locked(new_page);
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__SetPageLocked(new_page);
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SetPageSwapBacked(new_page);
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err = __add_to_swap_cache(new_page, entry);
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if (likely(!err)) {
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@ -367,7 +367,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
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}
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radix_tree_preload_end();
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ClearPageSwapBacked(new_page);
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__clear_page_locked(new_page);
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__ClearPageLocked(new_page);
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/*
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* add_to_swap_cache() doesn't return -EEXIST, so we can safely
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* clear SWAP_HAS_CACHE flag.
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@ -1184,7 +1184,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
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* we obviously don't have to worry about waking up a process
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* waiting on the page lock, because there are no references.
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*/
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__clear_page_locked(page);
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__ClearPageLocked(page);
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free_it:
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nr_reclaimed++;
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