The patch titled
Subject: mm/swapfile: mark racy access on si->highest_bit
has been added to the -mm mm-unstable branch. Its filename is
mm-swapfile-mark-racy-access-on-si-highest_bit.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swapfile-mark-racy-access-on-si-highest_bit.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: linke li <lilinke99@xxxxxx>
Subject: mm/swapfile: mark racy access on si->highest_bit
Date: Sat, 27 Apr 2024 14:29:56 +0800
In scan_swap_map_slots(), si->highest_bit can by changed by
swap_range_alloc() concurrently. All reads on si->highest_bit except one
is either protected by lock or read using READ_ONCE. So mark the one racy
read on si->highest_bit as benign using READ_ONCE.
This patch is aimed at reducing the number of benign races reported by
KCSAN in order to focus future debugging effort on harmful races.
Link: https://lkml.kernel.org/r/tencent_912BC3E8B0291DA4A0028AB424076375DA07@xxxxxx
Signed-off-by: linke li <lilinke99@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/swapfile.c~mm-swapfile-mark-racy-access-on-si-highest_bit
+++ a/mm/swapfile.c
@@ -902,7 +902,7 @@ static int scan_swap_map_slots(struct sw
last_in_cluster = offset + SWAPFILE_CLUSTER - 1;
/* Locate the first empty (unaligned) cluster */
- for (; last_in_cluster <= si->highest_bit; offset++) {
+ for (; last_in_cluster <= READ_ONCE(si->highest_bit); offset++) {
if (si->swap_map[offset])
last_in_cluster = offset + SWAPFILE_CLUSTER;
else if (offset == last_in_cluster) {
_
Patches currently in -mm which might be from lilinke99@xxxxxx are
mm-swapfile-mark-racy-access-on-si-highest_bit.patch
