From: linke li <lilinke99@qq.com>
Cc: xujianhao01@gmail.com, linke li <lilinke99@qq.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH] mm/swapfile: mark racy access on si->highest_bit
Date: Sat, 27 Apr 2024 14:29:56 +0800 [thread overview]
Message-ID: <tencent_912BC3E8B0291DA4A0028AB424076375DA07@qq.com> (raw)
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.
Signed-off-by: linke li <lilinke99@qq.com>
---
mm/swapfile.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 556ff7347d5f..fb2243f7f06b 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -854,7 +854,7 @@ static int scan_swap_map_slots(struct swap_info_struct *si,
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) {
--
2.39.3 (Apple Git-146)
reply other threads:[~2024-04-27 6:30 UTC|newest]
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