Re: [Syzkaller & bisect] There is INFO: task hung in __rq_qos_throttle

[Lai, Yi]

On Wed, Oct 23, 2024 at 09:57:53PM -0400, Kent Overstreet wrote:
> On Mon, Oct 21, 2024 at 06:27:25PM +0800, Lai, Yi wrote:
> > Hi Kent Overstreet,
> > 
> > Greetings!
> > 
> > I used Syzkaller and found that there is INFO: task hung in __rq_qos_throttle in v6.12-rc2
> > 
> > After bisection and the first bad commit is:
> > "
> > 63332394c7e1 bcachefs: Move snapshot table size to struct snapshot_table
> 
> You sure...?
> 
> Look at the patch, that's a pretty unlikely culprit; we would've seen
> something from kasan, and anyways there's guards on the new memory
> accesses/array derefs.
> 
> I've been seeing that bug too, but it's very intermittent. How did you
> get it to trigger reliably enough for a bisect?

Look into my local bisection log. You are right, that the bug is intermittent
and takes a very long time to reproduce the issue.

I didn't observe similar issues during following v6.12-rcx kernel
fuzzing. I will keep monitoring.

Regards,
Yi Lai