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 <paulmck@xxxxxxxxxxxxxxxxxx> > > > > 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.slusarz@xxxxxxxxx> > > > > Reported-by: David Rientjes <rientjes@xxxxxxxxxx> > > > > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> > > > > > > Acked-by: David Rientjes <rientjes@xxxxxxxxxx> > > > > 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.slusarz@xxxxxxxxx> Thanks, Marcin -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>