On Thu, 2017-08-24 at 21:56 +0200, Jiri Kosina wrote:
> On Thu, 24 Aug 2017, Luca Coelho wrote:
>
> > > Work queues cannot be allocated when a mutex is held because the mutex
> > > may be in use and that would make it sleep. Doing so generates the
> > > following splat with 4.13+:
> > >
> > > [ 19.513298] ======================================================
> > > [ 19.513429] WARNING: possible circular locking dependency detected
> > > [ 19.513557] 4.13.0-rc5+ #6 Not tainted
> > > [ 19.513638] ------------------------------------------------------
> > > [ 19.513767] cpuhp/0/12 is trying to acquire lock:
> > > [ 19.513867] (&tz->lock){+.+.+.}, at: [<ffffffff924afebb>] thermal_zone_get_temp+0x5b/0xb0
> > > [ 19.514047]
> > > [ 19.514047] but task is already holding lock:
> > > [ 19.514166] (cpuhp_state){+.+.+.}, at: [<ffffffff91cc4baa>] cpuhp_thread_fun+0x3a/0x210
> > > [ 19.514338]
> > > [ 19.514338] which lock already depends on the new lock.
> > >
> > > This lock dependency already existed with previous kernel versions,
> > > but it was not detected until commit 49dfe2a67797 ("cpuhotplug: Link
> > > lock stacks for hotplug callbacks") was introduced.
> > >
> > > Reported-by: David Weinehall <david.weinehall@xxxxxxxxx>
> > > Reported-by: Jiri Kosina <jikos@xxxxxxxxxx>
> > > Signed-off-by: Luca Coelho <luciano.coelho@xxxxxxxxx>
> >
> > Jiri, did you have a chance to try this out? I'm about to ask Kalle to
> > merge this so it gets in in time for 4.13-rc7.
>
> Sorry, I am almost completely offline for one more week (vacation), and
> will not have access to the affected system before that.
Sounds good! Enjoy! ;)
> But this indeed
> looks like a correct fix to me, so feel free to add
>
> Acked-by: Jiri Kosina <jkosina@xxxxxxx>
>
> I'll be able to provide my Tested-by: eventually only in ~10 days.
Kalle already picked it up in wireless-drivers and this should make it's
way to 4.13-rc7 (we hope).
In any case, thanks for reporting and the help debugging it.
--
Cheers,
Luca.
