From: Hugh Dickins Date: Sun, 25 Aug 2024 22:42:45 +0000 (-0700) Subject: mm: shmem: fix minor off-by-one in shrinkable calculation X-Git-Tag: v6.12-rc1~115^2~102 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=de5b85262e2038a5ae5d281ddf43d35acb2bfa60;p=thirdparty%2Fkernel%2Flinux.git mm: shmem: fix minor off-by-one in shrinkable calculation 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 Reviewed-by: David Hildenbrand Reviewed-by: Baolin Wang Signed-off-by: Andrew Morton --- diff --git a/mm/shmem.c b/mm/shmem.c index 800cec9dc534e..bf50ecb906ce2 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2348,7 +2348,7 @@ 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); /*