From 0416f3be58c6b1ea066cd52e354b857693feb01e Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Thu, 2 Feb 2023 10:18:04 +0800 Subject: blk-cgroup: don't update io stat for root cgroup We source root cgroup stats from the system-wide stats, see blkcg_print_stat and blkcg_rstat_flush, so don't update io state for root cgroup. Fixes blkg leak issue introduced in commit 3b8cc6298724 ("blk-cgroup: Optimize blkcg_rstat_flush()") which starts to grab blkg's reference when adding iostat_cpu into percpu blkcg list, but this state won't be consumed by blkcg_rstat_flush() where the blkg reference is dropped. Tested-by: Bart van Assche Reported-by: Bart van Assche Fixes: 3b8cc6298724 ("blk-cgroup: Optimize blkcg_rstat_flush()") Cc: Tejun Heo Cc: Waiman Long Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20230202021804.278582-1-ming.lei@redhat.com Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'block/blk-cgroup.c') diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 4c94a6560f62..9ac1efb053e0 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -2001,6 +2001,10 @@ void blk_cgroup_bio_start(struct bio *bio) struct blkg_iostat_set *bis; unsigned long flags; + /* Root-level stats are sourced from system-wide IO stats */ + if (!cgroup_parent(blkcg->css.cgroup)) + return; + cpu = get_cpu(); bis = per_cpu_ptr(bio->bi_blkg->iostat_cpu, cpu); flags = u64_stats_update_begin_irqsave(&bis->sync); -- cgit