From cabacb18a42db34bc676d1922e34bcbdbf1b2daa Mon Sep 17 00:00:00 2001
From: Baolin Wang <baolin.wang@linux.alibaba.com>
Date: Thu, 19 Dec 2024 15:30:09 +0800
Subject: [PATCH] mm: shmem: fix the update of 'shmem_falloc->nr_unswapped'
commit d77b90d2b2642655b5f60953c36ad887257e1802 upstream.
The 'shmem_falloc->nr_unswapped' is used to record how many writepage
refused to swap out because fallocate() is allocating, but after shmem
supports large folio swap out, the update of 'shmem_falloc->nr_unswapped'
does not use the correct number of pages in the large folio, which may
lead to fallocate() not exiting as soon as possible.
Anyway, this is found through code inspection, and I am not sure whether
it would actually cause serious issues.
Link: https://lkml.kernel.org/r/f66a0119d0564c2c37c84f045835b870d1b2196f.1734593154.git.baolin.wang@linux.alibaba.com
Fixes: 809bc86517cc ("mm: shmem: support large folio swap out")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/shmem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index b03ced0c3d485..21ef93c92b47f 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1527,7 +1527,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
!shmem_falloc->waitq &&
index >= shmem_falloc->start &&
index < shmem_falloc->next)
- shmem_falloc->nr_unswapped++;
+ shmem_falloc->nr_unswapped += nr_pages;
else
shmem_falloc = NULL;
spin_unlock(&inode->i_lock);
--
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