Re: Regression on linux-next (next-20260324 )

[Peter Zijlstra <peterz@infradead.org>]

On Mon, Mar 30, 2026 at 01:56:33PM +0530, Borah, Chaitanya Kumar wrote:
> > diff --git a/kernel/locking/ww_mutex.h b/kernel/locking/ww_mutex.h
> > index b1834ab7e782..bb8b410779d4 100644
> > --- a/kernel/locking/ww_mutex.h
> > +++ b/kernel/locking/ww_mutex.h
> > @@ -42,7 +42,7 @@ __ww_waiter_last(struct mutex *lock)
> >   	struct mutex_waiter *w = lock->first_waiter;
> >   	if (w)
> > -		w = list_prev_entry(w, list);
> > +		w = __ww_waiter_prev(lock, w);
> >   	return w;
> >   }
> Thank you for the response, Peter. Unfortunately, the issue is still seen
> with this change.

Bah, indeed. Looking at this after the weekend I see that it's actually
wrong.

But I haven't yet had a new idea. I don't suppose there is a relatively
easy way to reproduce this issue outside of your CI robot?

My current working thesis is that since this is graphics, this is
ww_mutex related. I'll go over this code once more...