Re: rcu_sched stall while waiting in csd_lock_wait()

[Pratyush Anand]

Hi Marc,

On Wednesday 02 August 2017 02:14 PM, Marc Zyngier wrote:
> On 02/08/17 09:08, Will Deacon wrote:
> > Hi Pratyush,
> >
> > On Wed, Aug 02, 2017 at 09:01:19AM +0530, Pratyush Anand wrote:
> > > I am observing following rcu_sched stall while executing `perf record -a  --
> > > sleep 1` with one of the arm64 platform. It looks like that stalled cpu was
> > > waiting in csd_lock_wait() from where it never came out,and so the stall.
> > > Any help/pointer for further debugging would be very helpful. Problem also
> > > reproduced with 4.13.0-rc3.
> >
> > When you say "also", which other kernel(s) show the problem? Is this a
> > recent regression? Which platform are you running on?
> >
> > It would be interesting to know what the other CPUs are doing, in particular
> > the target of the cross-call. Either it crashed spectacularly and didn't
> > unlock the csd lock, or the IPI somehow wasn't delivered.
> >
> > Do you see any other splats if you enable lock debugging?
>
> Also, is that in a guest, or bare metal? If that's a guest, what's the
> host's kernel version?

Its a host.
--
Regards
Pratyush