The patch titled
Subject: mm: thp: fix potential clearing to referenced flag in page_idle_clear_pte_refs_one()
has been removed from the -mm tree. Its filename was
mm-thp-fix-potential-clearing-to-referenced-flag-in-page_idle_clear_pte_refs_one.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Subject: 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.
So, here just break pvmw walk once referenced PTE is found if the page is
a part of THP.
Link: http://lkml.kernel.org/r/1517875596-76350-1-git-send-email-yang.shi@xxxxxxxxxxxxxxxxx
Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Reported-by: Gang Deng <gavin.dg@xxxxxxxxxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_idle.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff -puN mm/page_idle.c~mm-thp-fix-potential-clearing-to-referenced-flag-in-page_idle_clear_pte_refs_one mm/page_idle.c
--- a/mm/page_idle.c~mm-thp-fix-potential-clearing-to-referenced-flag-in-page_idle_clear_pte_refs_one
+++ a/mm/page_idle.c
@@ -67,6 +67,14 @@ static bool page_idle_clear_pte_refs_one
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 (referenced && PageTransCompound(pvmw.page)) {
+ page_vma_mapped_walk_done(&pvmw);
+ break;
+ }
} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
referenced = pmdp_clear_young_notify(vma, addr,
pvmw.pmd);
_
Patches currently in -mm which might be from yang.shi@xxxxxxxxxxxxxxxxx are
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