From 5ee9562c586cd4ca9402b3636157abdd58ab7978 Mon Sep 17 00:00:00 2001 From: linke li Date: Sat, 27 Apr 2024 14:29:56 +0800 Subject: mm/swapfile: mark racy access on si->highest_bit 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.com Signed-off-by: linke li Signed-off-by: Andrew Morton --- mm/swapfile.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/swapfile.c b/mm/swapfile.c index 96606580ee09..f6ca215fb92f 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -902,7 +902,7 @@ 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) { -- cgit v1.2.3