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Date:   Wed, 17 Aug 2022 07:57:07 -0400
From:   "Chris Murphy" <lists@colorremedies.com>
To:     =?UTF-8?Q?Holger_Hoffst=C3=A4tte?= <holger@applied-asynchrony.com>,
        "Nikolay Borisov" <nborisov@suse.com>,
        "Jens Axboe" <axboe@kernel.dk>, "Jan Kara" <jack@suse.cz>,
        "Paolo Valente" <paolo.valente@linaro.org>
Cc:     Linux-RAID <linux-raid@vger.kernel.org>,
        linux-block <linux-block@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "Josef Bacik" <josef@toxicpanda.com>
Subject: Re: stalling IO regression since linux 5.12, through 5.18
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On Wed, Aug 17, 2022, at 5:52 AM, Holger Hoffst=C3=A4tte wrote:
> On 2022-08-16 17:34, Chris Murphy wrote:
>>=20
>> 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
>>=20
>> 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=3Dio set.
>>=20
>> 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@hu=
aweicloud.com/
>
> on top of something more recent than 5.12? Ideally 5.19 where it appli=
es
> cleanly.

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


--=20
Chris Murphy