Re: stalling IO regression since linux 5.12, through 5.18

[Nikolay Borisov]

On 16.08.22 г. 17:22 ч., Chris Murphy wrote:
> On Sun, Aug 14, 2022, at 4:28 PM, Chris Murphy wrote:
> > On Fri, Aug 12, 2022, at 2:02 PM, Jens Axboe wrote:
> > > Might be worth trying to revert those from 5.12 to see if they are
> > > causing the issue? Jan, Paolo - does this ring any bells?
> >
> > git log --oneline --no-merges v5.11..c03c21ba6f4e > bisect.txt
> >
> > I tried checking out a33df75c6328, which is right before the first bfq
> > commit, but that kernel won't boot the hardware.
> >
> > Next I checked out v5.12, then reverted these commits in order (that
> > they were found in the bisect.txt file):
> >
> > 7684fbde4516 bfq: Use only idle IO periods for think time calculations
> > 28c6def00919 bfq: Use 'ttime' local variable
> > 41e76c85660c bfq: Avoid false bfq queue merging
> > > > > a5bf0a92e1b8 bfq: bfq_check_waker() should be static
> > 71217df39dc6 block, bfq: make waker-queue detection more robust
> > 5a5436b98d5c block, bfq: save also injection state on queue merging
> > e673914d52f9 block, bfq: save also weight-raised service on queue merging
> > d1f600fa4732 block, bfq: fix switch back from soft-rt weitgh-raising
> > 7f1995c27b19 block, bfq: re-evaluate convenience of I/O plugging on rq arrivals
> > eb2fd80f9d2c block, bfq: replace mechanism for evaluating I/O intensity
> > > > > 1a23e06cdab2 bfq: don't duplicate code for different paths
> > 2391d13ed484 block, bfq: do not expire a queue when it is the only busy
> > one
> > 3c337690d2eb block, bfq: avoid spurious switches to soft_rt of
> > interactive queues
> > 91b896f65d32 block, bfq: do not raise non-default weights
> > ab1fb47e33dc block, bfq: increase time window for waker detection
> > d4fc3640ff36 block, bfq: set next_rq to waker_bfqq->next_rq in waker
> > injection
> > b5f74ecacc31 block, bfq: use half slice_idle as a threshold to check
> > short ttime
> >
> > The two commits prefixed by >>> above were not previously mentioned by
> > Jens, but I reverted them anyway because they showed up in the git log
> > command.
> >
> > OK so, within 10 minutes the problem does happen still. This is
> > block/bfq-iosched.c resulting from the above reverts, in case anyone
> > wants to double check what I did:
> > https://drive.google.com/file/d/1ykU7MpmylJuXVobODWiiaLJk-XOiAjSt/view?usp=sharing
>
> Any suggestions for further testing? I could try go down farther in the bisect.txt list. The problem is if the hardware falls over on an unbootable kernel, I have to bug someone with LOM access. That's a limited resource.

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