From c164e038eee805147e95789dddb88ae3b3aca11c Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Wed, 10 Dec 2014 15:44:36 -0800 Subject: mm: fix huge zero page accounting in smaps report As a small zero page, huge zero page should not be accounted in smaps report as normal page. For small pages we rely on vm_normal_page() to filter out zero page, but vm_normal_page() is not designed to handle pmds. We only get here due hackish cast pmd to pte in smaps_pte_range() -- pte and pmd format is not necessary compatible on each and every architecture. Let's add separate codepath to handle pmds. follow_trans_huge_pmd() will detect huge zero page for us. We would need pmd_dirty() helper to do this properly. The patch adds it to THP-enabled architectures which don't yet have one. [akpm@linux-foundation.org: use do_div to fix 32-bit build] Signed-off-by: "Kirill A. Shutemov" Reported-by: Fengguang Wu Tested-by: Fengwei Yin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/task_mmu.c | 104 ++++++++++++++++++++++++++++++++++------------------- 1 file changed, 68 insertions(+), 36 deletions(-) (limited to 'fs/proc') diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index f6734c6b66a6..246eae84b13b 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -447,58 +447,91 @@ struct mem_size_stats { u64 pss; }; +static void smaps_account(struct mem_size_stats *mss, struct page *page, + unsigned long size, bool young, bool dirty) +{ + int mapcount; + + if (PageAnon(page)) + mss->anonymous += size; -static void smaps_pte_entry(pte_t ptent, unsigned long addr, - unsigned long ptent_size, struct mm_walk *walk) + mss->resident += size; + /* Accumulate the size in pages that have been accessed. */ + if (young || PageReferenced(page)) + mss->referenced += size; + mapcount = page_mapcount(page); + if (mapcount >= 2) { + u64 pss_delta; + + if (dirty || PageDirty(page)) + mss->shared_dirty += size; + else + mss->shared_clean += size; + pss_delta = (u64)size << PSS_SHIFT; + do_div(pss_delta, mapcount); + mss->pss += pss_delta; + } else { + if (dirty || PageDirty(page)) + mss->private_dirty += size; + else + mss->private_clean += size; + mss->pss += (u64)size << PSS_SHIFT; + } +} + +static void smaps_pte_entry(pte_t *pte, unsigned long addr, + struct mm_walk *walk) { struct mem_size_stats *mss = walk->private; struct vm_area_struct *vma = mss->vma; pgoff_t pgoff = linear_page_index(vma, addr); struct page *page = NULL; - int mapcount; - if (pte_present(ptent)) { - page = vm_normal_page(vma, addr, ptent); - } else if (is_swap_pte(ptent)) { - swp_entry_t swpent = pte_to_swp_entry(ptent); + if (pte_present(*pte)) { + page = vm_normal_page(vma, addr, *pte); + } else if (is_swap_pte(*pte)) { + swp_entry_t swpent = pte_to_swp_entry(*pte); if (!non_swap_entry(swpent)) - mss->swap += ptent_size; + mss->swap += PAGE_SIZE; else if (is_migration_entry(swpent)) page = migration_entry_to_page(swpent); - } else if (pte_file(ptent)) { - if (pte_to_pgoff(ptent) != pgoff) - mss->nonlinear += ptent_size; + } else if (pte_file(*pte)) { + if (pte_to_pgoff(*pte) != pgoff) + mss->nonlinear += PAGE_SIZE; } if (!page) return; - if (PageAnon(page)) - mss->anonymous += ptent_size; - if (page->index != pgoff) - mss->nonlinear += ptent_size; + mss->nonlinear += PAGE_SIZE; - mss->resident += ptent_size; - /* Accumulate the size in pages that have been accessed. */ - if (pte_young(ptent) || PageReferenced(page)) - mss->referenced += ptent_size; - mapcount = page_mapcount(page); - if (mapcount >= 2) { - if (pte_dirty(ptent) || PageDirty(page)) - mss->shared_dirty += ptent_size; - else - mss->shared_clean += ptent_size; - mss->pss += (ptent_size << PSS_SHIFT) / mapcount; - } else { - if (pte_dirty(ptent) || PageDirty(page)) - mss->private_dirty += ptent_size; - else - mss->private_clean += ptent_size; - mss->pss += (ptent_size << PSS_SHIFT); - } + smaps_account(mss, page, PAGE_SIZE, pte_young(*pte), pte_dirty(*pte)); +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr, + struct mm_walk *walk) +{ + struct mem_size_stats *mss = walk->private; + struct vm_area_struct *vma = mss->vma; + struct page *page; + + /* FOLL_DUMP will return -EFAULT on huge zero page */ + page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP); + if (IS_ERR_OR_NULL(page)) + return; + mss->anonymous_thp += HPAGE_PMD_SIZE; + smaps_account(mss, page, HPAGE_PMD_SIZE, + pmd_young(*pmd), pmd_dirty(*pmd)); } +#else +static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr, + struct mm_walk *walk) +{ +} +#endif static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, struct mm_walk *walk) @@ -509,9 +542,8 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, spinlock_t *ptl; if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { - smaps_pte_entry(*(pte_t *)pmd, addr, HPAGE_PMD_SIZE, walk); + smaps_pmd_entry(pmd, addr, walk); spin_unlock(ptl); - mss->anonymous_thp += HPAGE_PMD_SIZE; return 0; } @@ -524,7 +556,7 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, */ pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); for (; addr != end; pte++, addr += PAGE_SIZE) - smaps_pte_entry(*pte, addr, PAGE_SIZE, walk); + smaps_pte_entry(pte, addr, walk); pte_unmap_unlock(pte - 1, ptl); cond_resched(); return 0; -- cgit v1.2.1