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| author | Baolin Wang <baolin.wang@linux.alibaba.com> | 2021-01-28 13:58:15 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-02-13 13:52:56 +0100 |
| commit | 513fee2aee13cc4fd92dbeca0004581860c0ed26 (patch) | |
| tree | 17fdb5b578f715ccd39b82a2968fdafec5f29a54 /block | |
| parent | d1eb41833408f8f5d980ebcc37b15fd8e14632d9 (diff) | |
| download | linux-rt-513fee2aee13cc4fd92dbeca0004581860c0ed26.tar.gz | |
blk-cgroup: Use cond_resched() when destroy blkgs
[ Upstream commit 6c635caef410aa757befbd8857c1eadde5cc22ed ]
On !PREEMPT kernel, we can get below softlockup when doing stress
testing with creating and destroying block cgroup repeatly. The
reason is it may take a long time to acquire the queue's lock in
the loop of blkcg_destroy_blkgs(), or the system can accumulate a
huge number of blkgs in pathological cases. We can add a need_resched()
check on each loop and release locks and do cond_resched() if true
to avoid this issue, since the blkcg_destroy_blkgs() is not called
from atomic contexts.
[ 4757.010308] watchdog: BUG: soft lockup - CPU#11 stuck for 94s!
[ 4757.010698] Call trace:
[ 4757.010700] blkcg_destroy_blkgs+0x68/0x150
[ 4757.010701] cgwb_release_workfn+0x104/0x158
[ 4757.010702] process_one_work+0x1bc/0x3f0
[ 4757.010704] worker_thread+0x164/0x468
[ 4757.010705] kthread+0x108/0x138
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-cgroup.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 3d34ac02d76e..cb3d44d20005 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1089,6 +1089,8 @@ static void blkcg_css_offline(struct cgroup_subsys_state *css) */ void blkcg_destroy_blkgs(struct blkcg *blkcg) { + might_sleep(); + spin_lock_irq(&blkcg->lock); while (!hlist_empty(&blkcg->blkg_list)) { @@ -1096,14 +1098,20 @@ void blkcg_destroy_blkgs(struct blkcg *blkcg) struct blkcg_gq, blkcg_node); struct request_queue *q = blkg->q; - if (spin_trylock(&q->queue_lock)) { - blkg_destroy(blkg); - spin_unlock(&q->queue_lock); - } else { + if (need_resched() || !spin_trylock(&q->queue_lock)) { + /* + * Given that the system can accumulate a huge number + * of blkgs in pathological cases, check to see if we + * need to rescheduling to avoid softlockup. + */ spin_unlock_irq(&blkcg->lock); - cpu_relax(); + cond_resched(); spin_lock_irq(&blkcg->lock); + continue; } + + blkg_destroy(blkg); + spin_unlock(&q->queue_lock); } spin_unlock_irq(&blkcg->lock); |