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

[Kent Overstreet]

On Fri, Oct 25, 2024 at 05:52:57PM +0800, Lai, Yi wrote:
> 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.

yeah, this is one for Jens...