From d9104d1ca9662498339c0de975b4666c30485f4e Mon Sep 17 00:00:00 2001 From: Cyrill Gorcunov Date: Wed, 11 Sep 2013 14:22:24 -0700 Subject: mm: track vma changes with VM_SOFTDIRTY bit Pavel reported that in case if vma area get unmapped and then mapped (or expanded) in-place, the soft dirty tracker won't be able to recognize this situation since it works on pte level and ptes are get zapped on unmap, loosing soft dirty bit of course. So to resolve this situation we need to track actions on vma level, there VM_SOFTDIRTY flag comes in. When new vma area created (or old expanded) we set this bit, and keep it here until application calls for clearing soft dirty bit. Thus when user space application track memory changes now it can detect if vma area is renewed. Reported-by: Pavel Emelyanov Signed-off-by: Cyrill Gorcunov Cc: Andy Lutomirski Cc: Matt Mackall Cc: Xiao Guangrong Cc: Marcelo Tosatti Cc: KOSAKI Motohiro Cc: Stephen Rothwell Cc: Peter Zijlstra Cc: "Aneesh Kumar K.V" Cc: Rob Landley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/task_mmu.c | 46 ++++++++++++++++++++++++++++++++++++---------- 1 file changed, 36 insertions(+), 10 deletions(-) (limited to 'fs/proc') diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 107d026f5d6e..09228639b83d 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -740,6 +740,9 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma, ptent = pte_file_clear_soft_dirty(ptent); } + if (vma->vm_flags & VM_SOFTDIRTY) + vma->vm_flags &= ~VM_SOFTDIRTY; + set_pte_at(vma->vm_mm, addr, pte, ptent); #endif } @@ -949,13 +952,15 @@ static void pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm, if (is_migration_entry(entry)) page = migration_entry_to_page(entry); } else { - *pme = make_pme(PM_NOT_PRESENT(pm->v2)); + if (vma->vm_flags & VM_SOFTDIRTY) + flags2 |= __PM_SOFT_DIRTY; + *pme = make_pme(PM_NOT_PRESENT(pm->v2) | PM_STATUS2(pm->v2, flags2)); return; } if (page && !PageAnon(page)) flags |= PM_FILE; - if (pte_soft_dirty(pte)) + if ((vma->vm_flags & VM_SOFTDIRTY) || pte_soft_dirty(pte)) flags2 |= __PM_SOFT_DIRTY; *pme = make_pme(PM_PFRAME(frame) | PM_STATUS2(pm->v2, flags2) | flags); @@ -974,7 +979,7 @@ static void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *p *pme = make_pme(PM_PFRAME(pmd_pfn(pmd) + offset) | PM_STATUS2(pm->v2, pmd_flags2) | PM_PRESENT); else - *pme = make_pme(PM_NOT_PRESENT(pm->v2)); + *pme = make_pme(PM_NOT_PRESENT(pm->v2) | PM_STATUS2(pm->v2, pmd_flags2)); } #else static inline void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm, @@ -997,7 +1002,11 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, if (vma && pmd_trans_huge_lock(pmd, vma) == 1) { int pmd_flags2; - pmd_flags2 = (pmd_soft_dirty(*pmd) ? __PM_SOFT_DIRTY : 0); + if ((vma->vm_flags & VM_SOFTDIRTY) || pmd_soft_dirty(*pmd)) + pmd_flags2 = __PM_SOFT_DIRTY; + else + pmd_flags2 = 0; + for (; addr != end; addr += PAGE_SIZE) { unsigned long offset; @@ -1015,12 +1024,17 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, if (pmd_trans_unstable(pmd)) return 0; for (; addr != end; addr += PAGE_SIZE) { + int flags2; /* check to see if we've left 'vma' behind * and need a new, higher one */ if (vma && (addr >= vma->vm_end)) { vma = find_vma(walk->mm, addr); - pme = make_pme(PM_NOT_PRESENT(pm->v2)); + if (vma && (vma->vm_flags & VM_SOFTDIRTY)) + flags2 = __PM_SOFT_DIRTY; + else + flags2 = 0; + pme = make_pme(PM_NOT_PRESENT(pm->v2) | PM_STATUS2(pm->v2, flags2)); } /* check that 'vma' actually covers this address, @@ -1044,13 +1058,15 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, #ifdef CONFIG_HUGETLB_PAGE static void huge_pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm, - pte_t pte, int offset) + pte_t pte, int offset, int flags2) { if (pte_present(pte)) - *pme = make_pme(PM_PFRAME(pte_pfn(pte) + offset) - | PM_STATUS2(pm->v2, 0) | PM_PRESENT); + *pme = make_pme(PM_PFRAME(pte_pfn(pte) + offset) | + PM_STATUS2(pm->v2, flags2) | + PM_PRESENT); else - *pme = make_pme(PM_NOT_PRESENT(pm->v2)); + *pme = make_pme(PM_NOT_PRESENT(pm->v2) | + PM_STATUS2(pm->v2, flags2)); } /* This function walks within one hugetlb entry in the single call */ @@ -1059,12 +1075,22 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask, struct mm_walk *walk) { struct pagemapread *pm = walk->private; + struct vm_area_struct *vma; int err = 0; + int flags2; pagemap_entry_t pme; + vma = find_vma(walk->mm, addr); + WARN_ON_ONCE(!vma); + + if (vma && (vma->vm_flags & VM_SOFTDIRTY)) + flags2 = __PM_SOFT_DIRTY; + else + flags2 = 0; + for (; addr != end; addr += PAGE_SIZE) { int offset = (addr & ~hmask) >> PAGE_SHIFT; - huge_pte_to_pagemap_entry(&pme, pm, *pte, offset); + huge_pte_to_pagemap_entry(&pme, pm, *pte, offset, flags2); err = add_to_pagemap(addr, &pme, pm); if (err) return err; -- cgit v1.2.3-59-g8ed1b