+ mm-shmem-fix-minor-off-by-one-in-shrinkable-calculation.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

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@google.com>
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@google.com
Fixes: 779750d20b93 ("shmem: split huge pages beyond i_size under memory pressure")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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@google.com 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