The patch titled
Subject: mm: shmem: fix minor off-by-one in shrinkable calculation
has been added to the -mm mm-unstable branch. Its filename is
mm-shmem-fix-minor-off-by-one-in-shrinkable-calculation.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-shmem-fix-minor-off-by-one-in-shrinkable-calculation.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: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: mm: shmem: fix minor off-by-one in shrinkable calculation
Date: Sun, 25 Aug 2024 15:42:45 -0700 (PDT)
There has been a long-standing and very minor off-by-one, where
shmem_get_folio_gfp() decides if a large folio extends beyond i_size far
enough to leave a page or more for freeing later under pressure.
This is not something needed for stable: but it will be proportionately
more significant as support for smaller large folios is added, and is best
fixed before duplicating the check in other places.
Link: https://lkml.kernel.org/r/d8e75079-af2d-8519-56df-6be1dccc247a@xxxxxxxxxx
Fixes: 779750d20b93 ("shmem: split huge pages beyond i_size under memory pressure")
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/shmem.c~mm-shmem-fix-minor-off-by-one-in-shrinkable-calculation
+++ a/mm/shmem.c
@@ -2326,7 +2326,7 @@ alloced:
alloced = true;
if (folio_test_large(folio) &&
DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
- folio_next_index(folio) - 1) {
+ folio_next_index(folio)) {
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
struct shmem_inode_info *info = SHMEM_I(inode);
/*
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
mm-shmem-split-large-entry-if-the-swapin-folio-is-not-large-fix.patch
mm-shmem-fix-minor-off-by-one-in-shrinkable-calculation.patch
