Re: stalling IO regression since linux 5.12, through 5.18

Chris Murphy
2022-08-18T18:53:07Z

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