From: linke li lilinke99@qq.com
mainline inclusion from mainline-v6.10-rc1 commit 5ee9562c586cd4ca9402b3636157abdd58ab7978 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAHY3K
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
--------------------------------
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@qq.co... Signed-off-by: linke li lilinke99@qq.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/swapfile.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c index 744e5c8bd66b..941a98e7ed39 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -896,7 +896,7 @@ 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) {