On Sun, Jul 19, 2015 at 11:58:18AM +0200, Marcin Ślusarz wrote:
> On Thu, Jul 16, 2015 at 02:01:56PM -0700, David Rientjes wrote:
> > On Wed, 15 Jul 2015, Paul E. McKenney wrote:
> >
> > > On Tue, Jul 14, 2015 at 04:48:24PM -0700, David Rientjes wrote:
> > > > On Tue, 14 Jul 2015, Paul E. McKenney wrote:
> > > >
> > > > > commit a1992f2f3b8e174d740a8f764d0d51344bed2eed
> > > > > Author: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> > > > > Date: Tue Jul 14 16:24:14 2015 -0700
> > > > >
> > > > > rcu: Don't disable CPU hotplug during OOM notifiers
> > > > >
> > > > > RCU's rcu_oom_notify() disables CPU hotplug in order to stabilize
> > > > > the
> > > > > list of online CPUs, which it traverses. However, this is
> > > > > completely
> > > > > pointless because smp_call_function_single() will quietly fail if
> > > > > invoked
> > > > > on an offline CPU. Because the count of requests is incremented
> > > > > in the
> > > > > rcu_oom_notify_cpu() function that is remotely invoked,
> > > > > everything works
> > > > > nicely even in the face of concurrent CPU-hotplug operations.
> > > > >
> > > > > Furthermore, in recent kernels, invoking get_online_cpus() from
> > > > > an OOM
> > > > > notifier can result in deadlock. This commit therefore removes
> > > > > the
> > > > > call to get_online_cpus() and put_online_cpus() from
> > > > > rcu_oom_notify().
> > > > >
> > > > > Reported-by: Marcin Ślusarz <marcin.slus...@gmail.com>
> > > > > Reported-by: David Rientjes <rient...@google.com>
> > > > > Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> > > >
> > > > Acked-by: David Rientjes <rient...@google.com>
> > >
> > > Thank you!
> > >
> > > Any news on whether or not it solves the problem?
> > >
> >
> > Marcin, is your lockdep violation reproducible? If so, does this patch
> > fix it?
>
> I finally found enough time today to test it. I can reproduce it without
> the above patch and can't with. So:
> Tested-by: Marcin Ślusarz <marcin.slus...@gmail.com>
Thank you, applied!
Thanx, Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
