From: Ming Lei ming.lei@redhat.com
[ Upstream commit 0416f3be58c6b1ea066cd52e354b857693feb01e ]
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 bvanassche@acm.org Reported-by: Bart van Assche bvanassche@acm.org Fixes: 3b8cc6298724 ("blk-cgroup: Optimize blkcg_rstat_flush()") Cc: Tejun Heo tj@kernel.org Cc: Waiman Long longman@redhat.com Signed-off-by: Ming Lei ming.lei@redhat.com Link: https://lore.kernel.org/r/20230202021804.278582-1-ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Stable-dep-of: ad7c3b41e86b ("blk-throttle: Fix io statistics for cgroup v1") Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-cgroup.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 2c7be256ff879..5ee0ae8ddbf6f 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -2008,6 +2008,10 @@ 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);