Re: linux-next crashes in scheduler on s390

[Peter Zijlstra]

On Wed, Jun 10, 2026 at 03:03:26PM +0200, Sven Schnelle wrote:
> Alexander Gordeev <agordeev@xxxxxxxxxxxxx> writes:
> 
> > Hi All,
> >
> > Since about June 1st we're getting strace test suite (make -j$(nproc) check)
> > crashes on s390 in linux-next. Those are pretty easy to reproduce, but I
> > have not been able to nail it down to the particular commit/merge.
> >
> > I am going to bisect it, but since we are approaching v7.1 release, any
> > hint would be greatly appreciated!
> > [..]
> 
> I bisected it to
> https://lore.kernel.org/all/20260511120627.944705718@xxxxxxxxxxxxx/
> ("[PATCH v2 08/10] sched/fair: Add newidle balance to pick_task_fair()")
> 
> Adding the patch proposed in
> https://lore.kernel.org/all/20260603095108.GA1684319@xxxxxxxxxxxxx/
> fixes the issue for me.
> 
> To reproduce, running the strace test suite seems enough. If required, I
> can try to figure out the exact test that crashes the kernel.

Oh sorry for the borkage and thanks for the pointer -- I clearly missed
that :-(.

I've just been staring at all this and while I think I prefer a slightly
different solution, I think I'm going to just apply that patch since its
fairly trivial and you've confirmed it works. And then I can go do the
alternative for the next cycle -- and hopefully not wreck it again :-).