Re: stalling IO regression since linux 5.12, through 5.18

Chris Murphy
2022-08-17T11:57:35Z

On Wed, Aug 17, 2022, at 5:52 AM, Holger Hoffstätte wrote:
> On 2022-08-16 17:34, Chris Murphy wrote:
>>
>> On Tue, Aug 16, 2022, at 11:25 AM, Nikolay Borisov wrote:
>>> How about changing the scheduler either mq-deadline or noop, just
>>> to see if this is also reproducible with a different scheduler. I
>>> guess noop would imply the blk cgroup controller is going to be
>>> disabled
>>
>> I already reported on that: always happens with bfq within an hour or
>> less. Doesn't happen with mq-deadline for ~25+ hours. Does happen
>> with bfq with the above patches removed. Does happen with
>> cgroup.disabled=io set.
>>
>> Sounds to me like it's something bfq depends on and is somehow
>> becoming perturbed in a way that mq-deadline does not, and has
>> changed between 5.11 and 5.12. I have no idea what's under bfq that
>> matches this description.
>
> Chris, just a shot in the dark but can you try the patch from
>
> https://lore.kernel.org/linux-block/20220803121504.212071-1-yukuai1@huaweicloud.com/
>
> on top of something more recent than 5.12? Ideally 5.19 where it applies
> cleanly.

The problem doesn't reliably reproduce on 5.19. A patch for 5.12..5.18 would be much more testable.

--
Chris Murphy