From 4b471e8898c3d0f5c97a3c73ac32d0549fe01c87 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Fri, 15 Jan 2016 16:53:39 -0800 Subject: mm, thp: remove infrastructure for handling splitting PMDs With new refcounting we don't need to mark PMDs splitting. Let's drop code to handle this. Signed-off-by: Kirill A. Shutemov Tested-by: Sasha Levin Tested-by: Aneesh Kumar K.V Acked-by: Vlastimil Babka Acked-by: Jerome Marchand Cc: Andrea Arcangeli Cc: Hugh Dickins Cc: Dave Hansen Cc: Mel Gorman Cc: Rik van Riel Cc: Naoya Horiguchi Cc: Steve Capper Cc: Johannes Weiner Cc: Michal Hocko Cc: Christoph Lameter Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_idle.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'mm/page_idle.c') diff --git a/mm/page_idle.c b/mm/page_idle.c index d5dd79041484..1c245d9027e3 100644 --- a/mm/page_idle.c +++ b/mm/page_idle.c @@ -61,8 +61,7 @@ static int page_idle_clear_pte_refs_one(struct page *page, bool referenced = false; if (unlikely(PageTransHuge(page))) { - pmd = page_check_address_pmd(page, mm, addr, - PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl); + pmd = page_check_address_pmd(page, mm, addr, &ptl); if (pmd) { referenced = pmdp_clear_young_notify(vma, addr, pmd); spin_unlock(ptl); -- cgit v1.2.3 From b20ce5e03b936be077463015661dcf52be274e5b Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Fri, 15 Jan 2016 16:54:37 -0800 Subject: mm: prepare page_referenced() and page_idle to new THP refcounting Both page_referenced() and page_idle_clear_pte_refs_one() assume that THP can only be mapped with PMD, so there's no reason to look on PTEs for PageTransHuge() pages. That's no true anymore: THP can be mapped with PTEs too. The patch removes PageTransHuge() test from the functions and opencode page table check. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Kirill A. Shutemov Cc: Vladimir Davydov Cc: Andrea Arcangeli Cc: Hugh Dickins Cc: Naoya Horiguchi Cc: Sasha Levin Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/huge_mm.h | 5 --- include/linux/mm.h | 23 ++++++---- mm/huge_memory.c | 73 ++++++++---------------------- mm/page_idle.c | 65 +++++++++++++++++++++++---- mm/rmap.c | 117 +++++++++++++++++++++++++++++++++--------------- mm/util.c | 14 ++++++ 6 files changed, 185 insertions(+), 112 deletions(-) (limited to 'mm/page_idle.c') diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 7aec5ee9cfdf..72cd942edb22 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -48,11 +48,6 @@ enum transparent_hugepage_flag { #endif }; -extern pmd_t *page_check_address_pmd(struct page *page, - struct mm_struct *mm, - unsigned long address, - spinlock_t **ptl); - #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT) #define HPAGE_PMD_NR (1<_mapcount, -1); } +int __page_mapcount(struct page *page); + static inline int page_mapcount(struct page *page) { - int ret; VM_BUG_ON_PAGE(PageSlab(page), page); - ret = atomic_read(&page->_mapcount) + 1; - if (PageCompound(page)) { - page = compound_head(page); - ret += atomic_read(compound_mapcount_ptr(page)) + 1; - if (PageDoubleMap(page)) - ret--; - } - return ret; + if (unlikely(PageCompound(page))) + return __page_mapcount(page); + return atomic_read(&page->_mapcount) + 1; +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +int total_mapcount(struct page *page); +#else +static inline int total_mapcount(struct page *page) +{ + return page_mapcount(page); } +#endif static inline int page_count(struct page *page) { diff --git a/mm/huge_memory.c b/mm/huge_memory.c index f283cb7c480e..ab544b145b52 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1649,46 +1649,6 @@ bool __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, return false; } -/* - * This function returns whether a given @page is mapped onto the @address - * in the virtual space of @mm. - * - * When it's true, this function returns *pmd with holding the page table lock - * and passing it back to the caller via @ptl. - * If it's false, returns NULL without holding the page table lock. - */ -pmd_t *page_check_address_pmd(struct page *page, - struct mm_struct *mm, - unsigned long address, - spinlock_t **ptl) -{ - pgd_t *pgd; - pud_t *pud; - pmd_t *pmd; - - if (address & ~HPAGE_PMD_MASK) - return NULL; - - pgd = pgd_offset(mm, address); - if (!pgd_present(*pgd)) - return NULL; - pud = pud_offset(pgd, address); - if (!pud_present(*pud)) - return NULL; - pmd = pmd_offset(pud, address); - - *ptl = pmd_lock(mm, pmd); - if (!pmd_present(*pmd)) - goto unlock; - if (pmd_page(*pmd) != page) - goto unlock; - if (pmd_trans_huge(*pmd)) - return pmd; -unlock: - spin_unlock(*ptl); - return NULL; -} - #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE) int hugepage_madvise(struct vm_area_struct *vma, @@ -3097,20 +3057,6 @@ static void unfreeze_page(struct anon_vma *anon_vma, struct page *page) } } -static int total_mapcount(struct page *page) -{ - int i, ret; - - ret = compound_mapcount(page); - for (i = 0; i < HPAGE_PMD_NR; i++) - ret += atomic_read(&page[i]._mapcount) + 1; - - if (PageDoubleMap(page)) - ret -= HPAGE_PMD_NR; - - return ret; -} - static int __split_huge_page_tail(struct page *head, int tail, struct lruvec *lruvec, struct list_head *list) { @@ -3211,6 +3157,25 @@ static void __split_huge_page(struct page *page, struct list_head *list) } } +int total_mapcount(struct page *page) +{ + int i, ret; + + VM_BUG_ON_PAGE(PageTail(page), page); + + if (likely(!PageCompound(page))) + return atomic_read(&page->_mapcount) + 1; + + ret = compound_mapcount(page); + if (PageHuge(page)) + return ret; + for (i = 0; i < HPAGE_PMD_NR; i++) + ret += atomic_read(&page[i]._mapcount) + 1; + if (PageDoubleMap(page)) + ret -= HPAGE_PMD_NR; + return ret; +} + /* * This function splits huge page into normal pages. @page can point to any * subpage of huge page to split. Split doesn't change the position of @page. diff --git a/mm/page_idle.c b/mm/page_idle.c index 1c245d9027e3..2c553ba969f8 100644 --- a/mm/page_idle.c +++ b/mm/page_idle.c @@ -56,23 +56,70 @@ static int page_idle_clear_pte_refs_one(struct page *page, { struct mm_struct *mm = vma->vm_mm; spinlock_t *ptl; + pgd_t *pgd; + pud_t *pud; pmd_t *pmd; pte_t *pte; bool referenced = false; - if (unlikely(PageTransHuge(page))) { - pmd = page_check_address_pmd(page, mm, addr, &ptl); - if (pmd) { - referenced = pmdp_clear_young_notify(vma, addr, pmd); + pgd = pgd_offset(mm, addr); + if (!pgd_present(*pgd)) + return SWAP_AGAIN; + pud = pud_offset(pgd, addr); + if (!pud_present(*pud)) + return SWAP_AGAIN; + pmd = pmd_offset(pud, addr); + + if (pmd_trans_huge(*pmd)) { + ptl = pmd_lock(mm, pmd); + if (!pmd_present(*pmd)) + goto unlock_pmd; + if (unlikely(!pmd_trans_huge(*pmd))) { spin_unlock(ptl); + goto map_pte; } + + if (pmd_page(*pmd) != page) + goto unlock_pmd; + + referenced = pmdp_clear_young_notify(vma, addr, pmd); + spin_unlock(ptl); + goto found; +unlock_pmd: + spin_unlock(ptl); + return SWAP_AGAIN; } else { - pte = page_check_address(page, mm, addr, &ptl, 0); - if (pte) { - referenced = ptep_clear_young_notify(vma, addr, pte); - pte_unmap_unlock(pte, ptl); - } + pmd_t pmde = *pmd; + + barrier(); + if (!pmd_present(pmde) || pmd_trans_huge(pmde)) + return SWAP_AGAIN; + + } +map_pte: + pte = pte_offset_map(pmd, addr); + if (!pte_present(*pte)) { + pte_unmap(pte); + return SWAP_AGAIN; } + + ptl = pte_lockptr(mm, pmd); + spin_lock(ptl); + + if (!pte_present(*pte)) { + pte_unmap_unlock(pte, ptl); + return SWAP_AGAIN; + } + + /* THP can be referenced by any subpage */ + if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) { + pte_unmap_unlock(pte, ptl); + return SWAP_AGAIN; + } + + referenced = ptep_clear_young_notify(vma, addr, pte); + pte_unmap_unlock(pte, ptl); +found: if (referenced) { clear_page_idle(page); /* diff --git a/mm/rmap.c b/mm/rmap.c index 31d8866fb562..6127c00b2262 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -814,58 +814,105 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma, spinlock_t *ptl; int referenced = 0; struct page_referenced_arg *pra = arg; + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; - if (unlikely(PageTransHuge(page))) { - pmd_t *pmd; - - /* - * rmap might return false positives; we must filter - * these out using page_check_address_pmd(). - */ - pmd = page_check_address_pmd(page, mm, address, &ptl); - if (!pmd) + if (unlikely(PageHuge(page))) { + /* when pud is not present, pte will be NULL */ + pte = huge_pte_offset(mm, address); + if (!pte) return SWAP_AGAIN; - if (vma->vm_flags & VM_LOCKED) { + ptl = huge_pte_lockptr(page_hstate(page), mm, pte); + goto check_pte; + } + + pgd = pgd_offset(mm, address); + if (!pgd_present(*pgd)) + return SWAP_AGAIN; + pud = pud_offset(pgd, address); + if (!pud_present(*pud)) + return SWAP_AGAIN; + pmd = pmd_offset(pud, address); + + if (pmd_trans_huge(*pmd)) { + int ret = SWAP_AGAIN; + + ptl = pmd_lock(mm, pmd); + if (!pmd_present(*pmd)) + goto unlock_pmd; + if (unlikely(!pmd_trans_huge(*pmd))) { spin_unlock(ptl); + goto map_pte; + } + + if (pmd_page(*pmd) != page) + goto unlock_pmd; + + if (vma->vm_flags & VM_LOCKED) { pra->vm_flags |= VM_LOCKED; - return SWAP_FAIL; /* To break the loop */ + ret = SWAP_FAIL; /* To break the loop */ + goto unlock_pmd; } if (pmdp_clear_flush_young_notify(vma, address, pmd)) referenced++; spin_unlock(ptl); + goto found; +unlock_pmd: + spin_unlock(ptl); + return ret; } else { - pte_t *pte; + pmd_t pmde = *pmd; - /* - * rmap might return false positives; we must filter - * these out using page_check_address(). - */ - pte = page_check_address(page, mm, address, &ptl, 0); - if (!pte) + barrier(); + if (!pmd_present(pmde) || pmd_trans_huge(pmde)) return SWAP_AGAIN; + } +map_pte: + pte = pte_offset_map(pmd, address); + if (!pte_present(*pte)) { + pte_unmap(pte); + return SWAP_AGAIN; + } - if (vma->vm_flags & VM_LOCKED) { - pte_unmap_unlock(pte, ptl); - pra->vm_flags |= VM_LOCKED; - return SWAP_FAIL; /* To break the loop */ - } + ptl = pte_lockptr(mm, pmd); +check_pte: + spin_lock(ptl); - if (ptep_clear_flush_young_notify(vma, address, pte)) { - /* - * Don't treat a reference through a sequentially read - * mapping as such. If the page has been used in - * another mapping, we will catch it; if this other - * mapping is already gone, the unmap path will have - * set PG_referenced or activated the page. - */ - if (likely(!(vma->vm_flags & VM_SEQ_READ))) - referenced++; - } + if (!pte_present(*pte)) { + pte_unmap_unlock(pte, ptl); + return SWAP_AGAIN; + } + + /* THP can be referenced by any subpage */ + if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) { + pte_unmap_unlock(pte, ptl); + return SWAP_AGAIN; + } + + if (vma->vm_flags & VM_LOCKED) { pte_unmap_unlock(pte, ptl); + pra->vm_flags |= VM_LOCKED; + return SWAP_FAIL; /* To break the loop */ } + if (ptep_clear_flush_young_notify(vma, address, pte)) { + /* + * Don't treat a reference through a sequentially read + * mapping as such. If the page has been used in + * another mapping, we will catch it; if this other + * mapping is already gone, the unmap path will have + * set PG_referenced or activated the page. + */ + if (likely(!(vma->vm_flags & VM_SEQ_READ))) + referenced++; + } + pte_unmap_unlock(pte, ptl); + +found: if (referenced) clear_page_idle(page); if (test_and_clear_page_young(page)) @@ -912,7 +959,7 @@ int page_referenced(struct page *page, int ret; int we_locked = 0; struct page_referenced_arg pra = { - .mapcount = page_mapcount(page), + .mapcount = total_mapcount(page), .memcg = memcg, }; struct rmap_walk_control rwc = { diff --git a/mm/util.c b/mm/util.c index 8acb936a52c8..6d1f9200f74e 100644 --- a/mm/util.c +++ b/mm/util.c @@ -407,6 +407,20 @@ struct address_space *page_mapping(struct page *page) return mapping; } +/* Slow path of page_mapcount() for compound pages */ +int __page_mapcount(struct page *page) +{ + int ret; + + ret = atomic_read(&page->_mapcount) + 1; + page = compound_head(page); + ret += atomic_read(compound_mapcount_ptr(page)) + 1; + if (PageDoubleMap(page)) + ret--; + return ret; +} +EXPORT_SYMBOL_GPL(__page_mapcount); + int overcommit_ratio_handler(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) -- cgit v1.2.3 From 8749cfea11f3fffe8f7cad891470a77b36e0185f Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Fri, 15 Jan 2016 16:54:45 -0800 Subject: mm: add page_check_address_transhuge() helper page_referenced_one() and page_idle_clear_pte_refs_one() duplicate the code for looking up pte of a (possibly transhuge) page. Move this code to a new helper function, page_check_address_transhuge(), and make the above mentioned functions use it. This is just a cleanup, no functional changes are intended. Signed-off-by: Vladimir Davydov Reviewed-by: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/rmap.h | 19 +++++++++ mm/page_idle.c | 63 ++++------------------------ mm/rmap.c | 115 +++++++++++++++++++++++++++++++-------------------- 3 files changed, 99 insertions(+), 98 deletions(-) (limited to 'mm/page_idle.c') diff --git a/include/linux/rmap.h b/include/linux/rmap.h index ebf3750e42b2..77d1ba57d495 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -215,6 +215,25 @@ static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm, return ptep; } +/* + * Used by idle page tracking to check if a page was referenced via page + * tables. + */ +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +bool page_check_address_transhuge(struct page *page, struct mm_struct *mm, + unsigned long address, pmd_t **pmdp, + pte_t **ptep, spinlock_t **ptlp); +#else +static inline bool page_check_address_transhuge(struct page *page, + struct mm_struct *mm, unsigned long address, + pmd_t **pmdp, pte_t **ptep, spinlock_t **ptlp) +{ + *ptep = page_check_address(page, mm, address, ptlp, 0); + *pmdp = NULL; + return !!*ptep; +} +#endif + /* * Used by swapoff to help locate where page is expected in vma. */ diff --git a/mm/page_idle.c b/mm/page_idle.c index 2c553ba969f8..4ea9c4ef5146 100644 --- a/mm/page_idle.c +++ b/mm/page_idle.c @@ -55,71 +55,26 @@ static int page_idle_clear_pte_refs_one(struct page *page, unsigned long addr, void *arg) { struct mm_struct *mm = vma->vm_mm; - spinlock_t *ptl; - pgd_t *pgd; - pud_t *pud; pmd_t *pmd; pte_t *pte; + spinlock_t *ptl; bool referenced = false; - pgd = pgd_offset(mm, addr); - if (!pgd_present(*pgd)) - return SWAP_AGAIN; - pud = pud_offset(pgd, addr); - if (!pud_present(*pud)) + if (!page_check_address_transhuge(page, mm, addr, &pmd, &pte, &ptl)) return SWAP_AGAIN; - pmd = pmd_offset(pud, addr); - - if (pmd_trans_huge(*pmd)) { - ptl = pmd_lock(mm, pmd); - if (!pmd_present(*pmd)) - goto unlock_pmd; - if (unlikely(!pmd_trans_huge(*pmd))) { - spin_unlock(ptl); - goto map_pte; - } - - if (pmd_page(*pmd) != page) - goto unlock_pmd; + if (pte) { + referenced = ptep_clear_young_notify(vma, addr, pte); + pte_unmap(pte); + } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { referenced = pmdp_clear_young_notify(vma, addr, pmd); - spin_unlock(ptl); - goto found; -unlock_pmd: - spin_unlock(ptl); - return SWAP_AGAIN; } else { - pmd_t pmde = *pmd; - - barrier(); - if (!pmd_present(pmde) || pmd_trans_huge(pmde)) - return SWAP_AGAIN; - - } -map_pte: - pte = pte_offset_map(pmd, addr); - if (!pte_present(*pte)) { - pte_unmap(pte); - return SWAP_AGAIN; + /* unexpected pmd-mapped page? */ + WARN_ON_ONCE(1); } - ptl = pte_lockptr(mm, pmd); - spin_lock(ptl); - - if (!pte_present(*pte)) { - pte_unmap_unlock(pte, ptl); - return SWAP_AGAIN; - } - - /* THP can be referenced by any subpage */ - if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) { - pte_unmap_unlock(pte, ptl); - return SWAP_AGAIN; - } + spin_unlock(ptl); - referenced = ptep_clear_young_notify(vma, addr, pte); - pte_unmap_unlock(pte, ptl); -found: if (referenced) { clear_page_idle(page); /* diff --git a/mm/rmap.c b/mm/rmap.c index 6127c00b2262..cdc2a885a4cd 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -798,48 +798,44 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) return 1; } -struct page_referenced_arg { - int mapcount; - int referenced; - unsigned long vm_flags; - struct mem_cgroup *memcg; -}; +#ifdef CONFIG_TRANSPARENT_HUGEPAGE /* - * arg: page_referenced_arg will be passed + * Check that @page is mapped at @address into @mm. In contrast to + * page_check_address(), this function can handle transparent huge pages. + * + * On success returns true with pte mapped and locked. For PMD-mapped + * transparent huge pages *@ptep is set to NULL. */ -static int page_referenced_one(struct page *page, struct vm_area_struct *vma, - unsigned long address, void *arg) +bool page_check_address_transhuge(struct page *page, struct mm_struct *mm, + unsigned long address, pmd_t **pmdp, + pte_t **ptep, spinlock_t **ptlp) { - struct mm_struct *mm = vma->vm_mm; - spinlock_t *ptl; - int referenced = 0; - struct page_referenced_arg *pra = arg; pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t *pte; + spinlock_t *ptl; if (unlikely(PageHuge(page))) { /* when pud is not present, pte will be NULL */ pte = huge_pte_offset(mm, address); if (!pte) - return SWAP_AGAIN; + return false; ptl = huge_pte_lockptr(page_hstate(page), mm, pte); + pmd = NULL; goto check_pte; } pgd = pgd_offset(mm, address); if (!pgd_present(*pgd)) - return SWAP_AGAIN; + return false; pud = pud_offset(pgd, address); if (!pud_present(*pud)) - return SWAP_AGAIN; + return false; pmd = pmd_offset(pud, address); if (pmd_trans_huge(*pmd)) { - int ret = SWAP_AGAIN; - ptl = pmd_lock(mm, pmd); if (!pmd_present(*pmd)) goto unlock_pmd; @@ -851,31 +847,23 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma, if (pmd_page(*pmd) != page) goto unlock_pmd; - if (vma->vm_flags & VM_LOCKED) { - pra->vm_flags |= VM_LOCKED; - ret = SWAP_FAIL; /* To break the loop */ - goto unlock_pmd; - } - - if (pmdp_clear_flush_young_notify(vma, address, pmd)) - referenced++; - spin_unlock(ptl); + pte = NULL; goto found; unlock_pmd: spin_unlock(ptl); - return ret; + return false; } else { pmd_t pmde = *pmd; barrier(); if (!pmd_present(pmde) || pmd_trans_huge(pmde)) - return SWAP_AGAIN; + return false; } map_pte: pte = pte_offset_map(pmd, address); if (!pte_present(*pte)) { pte_unmap(pte); - return SWAP_AGAIN; + return false; } ptl = pte_lockptr(mm, pmd); @@ -884,35 +872,74 @@ check_pte: if (!pte_present(*pte)) { pte_unmap_unlock(pte, ptl); - return SWAP_AGAIN; + return false; } /* THP can be referenced by any subpage */ if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) { pte_unmap_unlock(pte, ptl); - return SWAP_AGAIN; + return false; } +found: + *ptep = pte; + *pmdp = pmd; + *ptlp = ptl; + return true; +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + +struct page_referenced_arg { + int mapcount; + int referenced; + unsigned long vm_flags; + struct mem_cgroup *memcg; +}; +/* + * arg: page_referenced_arg will be passed + */ +static int page_referenced_one(struct page *page, struct vm_area_struct *vma, + unsigned long address, void *arg) +{ + struct mm_struct *mm = vma->vm_mm; + struct page_referenced_arg *pra = arg; + pmd_t *pmd; + pte_t *pte; + spinlock_t *ptl; + int referenced = 0; + + if (!page_check_address_transhuge(page, mm, address, &pmd, &pte, &ptl)) + return SWAP_AGAIN; if (vma->vm_flags & VM_LOCKED) { - pte_unmap_unlock(pte, ptl); + if (pte) + pte_unmap(pte); + spin_unlock(ptl); pra->vm_flags |= VM_LOCKED; return SWAP_FAIL; /* To break the loop */ } - if (ptep_clear_flush_young_notify(vma, address, pte)) { - /* - * Don't treat a reference through a sequentially read - * mapping as such. If the page has been used in - * another mapping, we will catch it; if this other - * mapping is already gone, the unmap path will have - * set PG_referenced or activated the page. - */ - if (likely(!(vma->vm_flags & VM_SEQ_READ))) + if (pte) { + if (ptep_clear_flush_young_notify(vma, address, pte)) { + /* + * Don't treat a reference through a sequentially read + * mapping as such. If the page has been used in + * another mapping, we will catch it; if this other + * mapping is already gone, the unmap path will have + * set PG_referenced or activated the page. + */ + if (likely(!(vma->vm_flags & VM_SEQ_READ))) + referenced++; + } + pte_unmap(pte); + } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { + if (pmdp_clear_flush_young_notify(vma, address, pmd)) referenced++; + } else { + /* unexpected pmd-mapped page? */ + WARN_ON_ONCE(1); } - pte_unmap_unlock(pte, ptl); + spin_unlock(ptl); -found: if (referenced) clear_page_idle(page); if (test_and_clear_page_young(page)) -- cgit v1.2.3