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authorYang Shi <yang.shi@linux.alibaba.com>2018-04-05 16:22:35 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-05 21:36:25 -0700
commitf0849ac0b8e072073ec5fcc7fadd05a77434364e (patch)
tree482a57307a9333e6c43a674056ea73e5643b26e8
parentc9e97a1997fbf3a1d18d4065c2ca381f0704d7e5 (diff)
downloadlinux-f0849ac0b8e072073ec5fcc7fadd05a77434364e.tar.bz2
mm: thp: fix potential clearing to referenced flag in page_idle_clear_pte_refs_one()
For PTE-mapped THP, the compound THP has not been split to normal 4K pages yet, the whole THP is considered referenced if any one of sub page is referenced. When walking PTE-mapped THP by pvmw, all relevant PTEs will be checked to retrieve referenced bit. But, the current code just returns the result of the last PTE. If the last PTE has not referenced, the referenced flag will be cleared. Just set referenced when ptep{pmdp}_clear_young_notify() returns true. Link: http://lkml.kernel.org/r/1518212451-87134-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Reported-by: Gang Deng <gavin.dg@linux.alibaba.com> Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page_idle.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/mm/page_idle.c b/mm/page_idle.c
index 0a49374e6931..e412a63b2b74 100644
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -65,11 +65,15 @@ static bool page_idle_clear_pte_refs_one(struct page *page,
while (page_vma_mapped_walk(&pvmw)) {
addr = pvmw.address;
if (pvmw.pte) {
- referenced = ptep_clear_young_notify(vma, addr,
- pvmw.pte);
+ /*
+ * For PTE-mapped THP, one sub page is referenced,
+ * the whole THP is referenced.
+ */
+ if (ptep_clear_young_notify(vma, addr, pvmw.pte))
+ referenced = true;
} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
- referenced = pmdp_clear_young_notify(vma, addr,
- pvmw.pmd);
+ if (pmdp_clear_young_notify(vma, addr, pvmw.pmd))
+ referenced = true;
} else {
/* unexpected pmd-mapped page? */
WARN_ON_ONCE(1);