On Fri, Jan 22, 2016 at 10:51:04AM -0500, Tejun Heo wrote: > On Fri, Jan 22, 2016 at 09:48:54AM -0500, Johannes Weiner wrote: > > On Fri, Jan 22, 2016 at 04:50:42PM +0300, Vladimir Davydov wrote: > > > From first glance, it looks like the bug was triggered, because > > > mem_cgroup_css_offline was run for a child cgroup earlier than for its > > > parent. This couldn't happen for sure before the cgroup was switched to > > > percpu_ref, because cgroup_destroy_wq has always had max_active == 1. > > > Now, however, it looks like this is perfectly possible for > > > css_killed_ref_fn is called from an rcu callback - see kill_css -> > > > percpu_ref_kill_and_confirm. This breaks kmemcg assumptions. > > > > > > I'll take a look what can be done about that. > > > > It's an acknowledged problem in the cgroup core then, and not an issue > > with kmemcg. Tejun sent a fix to correct the offlining order here: > > > > https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1056544.html > > Patche descriptions updated and applied to cgroup/for-4.5-fixes. > > http://lkml.kernel.org/g/20160122154503.GD32380@xxxxxxxxxxxxxxx > http://lkml.kernel.org/g/20160122154552.GE32380@xxxxxxxxxxxxxxx I couldn't reproduce the issue with the two patches applied. Looks like they fix it. Thanks, Vladimir -- 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>