Re: [PATCH v2] hung_task: Dump blocker task if it is not hung

[Lance Yang]

On 2025/7/31 11:37, Sergey Senozhatsky wrote:
> On (25/07/31 11:25), Lance Yang wrote:
> > > > Wrote a simple 3 tasks circular lock test (same that I had in real
> > > > life).  The output looks good:
> > >
> > > Nice work! The log is now much clearer ;)
> >
> > Forgot to add:
> >
> > This circular lock test is great. It would be very valuable to have
> > it in samples/hung_task ;)
> >
> > Would you be willing to submit it as a patch?
>
> Well, that particular test is a deadlock, not sure how useful a test
> that deadlocks is going to be.  We probably need some alternative if
> we want to test backtrace de-dup.

Yep, you're right. A permanent deadlock is a no-go for a reusable test.

Maybe we need a test like a blocker chain (T1->T2->T3), where T3 holds
the lock and just sleeps for a while. Once it wakes up and releases the
lock, everything can finish cleanly.

Also, I might try to cook up a sample for that, time permitting ;)