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authorMing Lei <ming.lei@redhat.com>2023-02-02 05:18:04 +0300
committerJens Axboe <axboe@kernel.dk>2023-02-02 05:26:41 +0300
commit0416f3be58c6b1ea066cd52e354b857693feb01e (patch)
tree4c92b2739ef71e6f525743a9bb5f5e1c2dda61e8 /block
parent81ea42b9c3d61ea34d82d900ed93f4b4851f13b0 (diff)
downloadlinux-0416f3be58c6b1ea066cd52e354b857693feb01e.tar.xz
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 <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>
Diffstat (limited to 'block')
-rw-r--r--block/blk-cgroup.c4
1 files changed, 4 insertions, 0 deletions
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);