linux-kernel - Re: stalling IO regression since linux 5.12, through 5.18

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Message-Id: <bfaa8b43-519f-4e4c-b04b-a37b0ee9babf@www.fastmail.com>
Date:   Thu, 18 Aug 2022 14:52:34 -0400
From:   "Chris Murphy" <lists@...orremedies.com>
To:     "Ming Lei" <ming.lei@...hat.com>
Cc:     "Nikolay Borisov" <nborisov@...e.com>,
        "Jens Axboe" <axboe@...nel.dk>, "Jan Kara" <jack@...e.cz>,
        "Paolo Valente" <paolo.valente@...aro.org>,
        "Btrfs BTRFS" <linux-btrfs@...r.kernel.org>,
        Linux-RAID <linux-raid@...r.kernel.org>,
        linux-block <linux-block@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "Josef Bacik" <josef@...icpanda.com>
Subject: Re: stalling IO regression since linux 5.12, through 5.18



On Thu, Aug 18, 2022, at 1:15 AM, Ming Lei wrote:
> On Thu, Aug 18, 2022 at 12:27:04AM -0400, Chris Murphy wrote:
>> 
>> 
>> On Thu, Aug 18, 2022, at 12:18 AM, Chris Murphy wrote:
>> > On Thu, Aug 18, 2022, at 12:12 AM, Chris Murphy wrote:
>> >> On Wed, Aug 17, 2022, at 11:41 PM, Ming Lei wrote:
>> >>
>> >>> OK, can you post the blk-mq debugfs log after you trigger it on v5.17?
>> 
>> Same boot, 3rd log. But the load is above 300 so I kinda need to sysrq+b soon.
>> 
>> https://drive.google.com/file/d/1375H558kqPTdng439rvG6LuXXWPXLToo/view?usp=sharing
>> 
>
> Please test the following patch and see if it makes a difference:
>
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index a4f7c101b53b..8e8d77e79dd6 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -44,7 +44,10 @@ void __blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx)
>  	 */
>  	smp_mb();
> 
> -	blk_mq_run_hw_queue(hctx, true);
> +	if (blk_mq_is_shared_tags(hctx->flags))
> +		blk_mq_run_hw_queues(hctx->queue, true);
> +	else
> +		blk_mq_run_hw_queue(hctx, true);
>  }
> 
>  static int sched_rq_cmp(void *priv, const struct list_head *a,


I still get a stall. By the time I noticed it, I can't run any new commands (they just hang) so I had to sysrq+b. Let me know if I should rerun the test in order to capture block debug log.


-- 
Chris Murphy