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" <kirill@shutemov.name>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Tested-by: Fengwei Yin <yfw.kernel@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 41a43bf..df22314 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -279,6 +279,7 @@
#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#define pmd_dirty(pmd) pte_dirty(pmd_pte(pmd))
#define pmd_young(pmd) pte_young(pmd_pte(pmd))
#define pmd_wrprotect(pmd) pte_pmd(pte_wrprotect(pmd_pte(pmd)))
#define pmd_mksplitting(pmd) pte_pmd(pte_mkspecial(pmd_pte(pmd)))
diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h
index ae153c4..9b4b190 100644
--- a/arch/powerpc/include/asm/pgtable-ppc64.h
+++ b/arch/powerpc/include/asm/pgtable-ppc64.h
@@ -467,6 +467,7 @@
}
#define pmd_pfn(pmd) pte_pfn(pmd_pte(pmd))
+#define pmd_dirty(pmd) pte_dirty(pmd_pte(pmd))
#define pmd_young(pmd) pte_young(pmd_pte(pmd))
#define pmd_mkold(pmd) pte_pmd(pte_mkold(pmd_pte(pmd)))
#define pmd_wrprotect(pmd) pte_pmd(pte_wrprotect(pmd_pte(pmd)))
diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index bfeb626..1ff9e78 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -667,6 +667,13 @@
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline unsigned long pmd_dirty(pmd_t pmd)
+{
+ pte_t pte = __pte(pmd_val(pmd));
+
+ return pte_dirty(pte);
+}
+
static inline unsigned long pmd_young(pmd_t pmd)
{
pte_t pte = __pte(pmd_val(pmd));
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index aa97a07..081d6f4 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -99,6 +99,11 @@
return pte_flags(pte) & _PAGE_ACCESSED;
}
+static inline int pmd_dirty(pmd_t pmd)
+{
+ return pmd_flags(pmd) & _PAGE_DIRTY;
+}
+
static inline int pmd_young(pmd_t pmd)
{
return pmd_flags(pmd) & _PAGE_ACCESSED;
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index f6734c6..246eae8 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -447,59 +447,92 @@
u64 pss;
};
+static void smaps_account(struct mem_size_stats *mss, struct page *page,
+ unsigned long size, bool young, bool dirty)
+{
+ int mapcount;
-static void smaps_pte_entry(pte_t ptent, unsigned long addr,
- unsigned long ptent_size, struct mm_walk *walk)
+ if (PageAnon(page))
+ mss->anonymous += size;
+
+ 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 @@
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 @@
*/
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;