path: root/mm/memory.c
diff options
authorWill Deacon <>2012-12-11 16:01:27 -0800
committerLinus Torvalds <>2012-12-11 17:22:24 -0800
commita1dd450bcb1a05e8218b9aac0ee36f8755d8a140 (patch)
treea46f3306e3802b59ed5df6eef0e03b8b11cca30c /mm/memory.c
parenteb2db439a3203ae86c35ad277ac4a3268a94baa1 (diff)
mm: thp: set the accessed flag for old pages on access fault
On x86 memory accesses to pages without the ACCESSED flag set result in the ACCESSED flag being set automatically. With the ARM architecture a page access fault is raised instead (and it will continue to be raised until the ACCESSED flag is set for the appropriate PTE/PMD). For normal memory pages, handle_pte_fault will call pte_mkyoung (effectively setting the ACCESSED flag). For transparent huge pages, pmd_mkyoung will only be called for a write fault. This patch ensures that faults on transparent hugepages which do not result in a CoW update the access flags for the faulting pmd. Signed-off-by: Will Deacon <> Cc: Chris Metcalf <> Acked-by: Kirill A. Shutemov <> Cc: Andrea Arcangeli <> Acked-by: Johannes Weiner <> Cc: Ni zhan Chen <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/memory.c')
1 files changed, 6 insertions, 2 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 221fc9ffcab1..765377385632 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3537,8 +3537,9 @@ retry:
if (pmd_trans_huge(orig_pmd)) {
- if (flags & FAULT_FLAG_WRITE &&
- !pmd_write(orig_pmd) &&
+ unsigned int dirty = flags & FAULT_FLAG_WRITE;
+ if (dirty && !pmd_write(orig_pmd) &&
!pmd_trans_splitting(orig_pmd)) {
ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
@@ -3550,6 +3551,9 @@ retry:
if (unlikely(ret & VM_FAULT_OOM))
goto retry;
return ret;
+ } else {
+ huge_pmd_set_accessed(mm, vma, address, pmd,
+ orig_pmd, dirty);
return 0;