The patch titled
Subject: mm-hold-ptl-from-the-first-pte-while-reclaiming-a-large-folio-fix
has been added to the -mm mm-unstable branch. Its filename is
mm-hold-ptl-from-the-first-pte-while-reclaiming-a-large-folio-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hold-ptl-from-the-first-pte-while-reclaiming-a-large-folio-fix.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: mm-hold-ptl-from-the-first-pte-while-reclaiming-a-large-folio-fix
Date: Tue Mar 26 11:30:46 AM PDT 2024
rewrap comment, per Matthew
Cc: Barry Song <v-songbaohua@xxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
--- a/mm/vmscan.c~mm-hold-ptl-from-the-first-pte-while-reclaiming-a-large-folio-fix
+++ a/mm/vmscan.c
@@ -1258,14 +1258,16 @@ retry:
if (folio_test_pmd_mappable(folio))
flags |= TTU_SPLIT_HUGE_PMD;
/*
- * Without TTU_SYNC, try_to_unmap will only begin to hold PTL
- * from the first present PTE within a large folio. Some initial
- * PTEs might be skipped due to races with parallel PTE writes
- * in which PTEs can be cleared temporarily before being written
- * new present values. This will lead to a large folio is still
- * mapped while some subpages have been partially unmapped after
- * try_to_unmap; TTU_SYNC helps try_to_unmap acquire PTL from the
- * first PTE, eliminating the influence of temporary PTE values.
+ * Without TTU_SYNC, try_to_unmap will only begin to
+ * hold PTL from the first present PTE within a large
+ * folio. Some initial PTEs might be skipped due to
+ * races with parallel PTE writes in which PTEs can be
+ * cleared temporarily before being written new present
+ * values. This will lead to a large folio is still
+ * mapped while some subpages have been partially
+ * unmapped after try_to_unmap; TTU_SYNC helps
+ * try_to_unmap acquire PTL from the first PTE,
+ * eliminating the influence of temporary PTE values.
*/
if (folio_test_large(folio) && list_empty(&folio->_deferred_list))
flags |= TTU_SYNC;
_
Patches currently in -mm which might be from akpm@xxxxxxxxxxxxxxxxxxxx are
mm-sparc-change-pxd_huge-behavior-to-exclude-swap-entries-fix.patch
mm-hold-ptl-from-the-first-pte-while-reclaiming-a-large-folio-fix.patch
mm-move-follow_phys-to-arch-x86-mm-pat-memtypec-fix.patch
