Re: lockdep splat in CPU hotplug

[Daniel Lezcano]

On 10/22/2014 04:36 PM, Jiri Kosina wrote:
> On Wed, 22 Oct 2014, Daniel Lezcano wrote:
>
> > > > I am seeing the lockdep report below when resuming from suspend-to-disk
> > > > with current Linus' tree (c2661b80609).
> > > >
> > > > The reason for CCing Ingo and Peter is that I can't make any sense of one
> > > > of the stacktraces lockdep is providing.
> > > >
> > > > Please have a look at the very first stacktrace in the dump, where lockdep
> > > > is trying to explain where cpu_hotplug.lock#2 has been acquired. It seems
> > > > to imply that cpuidle_pause() is taking cpu_hotplug.lock, but that's not
> > > > the case at all.
> > > >
> > > > What am I missing?
> > >
> > > Okay, reverting 442bf3aaf55a ("sched: Let the scheduler see CPU idle
> > > states") and followup 83a0a96a5f26 ("sched/fair: Leverage the idle state
> > > info when choosing the "idlest" cpu") which depends on it makes the splat
> > > go away.
> >
> > Are you able to reproduce it by offlining the cpu and onlining it again ?
>
> No, that doesn't trigger it (please note that all the relevant stacktraces
> from lockdep are going through hibernation).

Ok, thanks.


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