From: Tao Cui blkg_rwstat_recursive_sum() reads pos_blkg->online without the queue lock that its doc comment requires, since blkcg_print_blkgs() stopped holding it in 56cc24f59c14. Concurrent blkg_create/destroy flips ->online, tripping KCSAN. The race is harmless (RCU-protected, stale online only causes minor stat noise). Use data_race() to annotate the intentional lockless read. Signed-off-by: Tao Cui --- block/blk-cgroup-rwstat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/blk-cgroup-rwstat.c b/block/blk-cgroup-rwstat.c index aae910713814..71f74052ae03 100644 --- a/block/blk-cgroup-rwstat.c +++ b/block/blk-cgroup-rwstat.c @@ -107,7 +107,7 @@ void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol, blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) { struct blkg_rwstat *rwstat; - if (!pos_blkg->online) + if (!data_race(pos_blkg->online)) continue; if (pol) { -- 2.43.0