+ mm-hold-ptl-from-the-first-pte-while-reclaiming-a-large-folio-fix.patch added to mm-unstable branch

+ mm-hold-ptl-from-the-first-pte-while-reclaiming-a-large-folio-fix.patch added to mm-unstable branch

[Andrew Morton]

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@linux-foundation.org>
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@oppo.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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@linux-foundation.org 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