From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f47.google.com (mail-wm0-f47.google.com [74.125.82.47]) by kanga.kvack.org (Postfix) with ESMTP id 56D056B0005 for ; Fri, 22 Jan 2016 09:49:07 -0500 (EST) Received: by mail-wm0-f47.google.com with SMTP id l65so263997475wmf.1 for ; Fri, 22 Jan 2016 06:49:07 -0800 (PST) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id p1si8809632wjx.81.2016.01.22.06.49.06 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 22 Jan 2016 06:49:06 -0800 (PST) Date: Fri, 22 Jan 2016 09:48:54 -0500 From: Johannes Weiner Subject: Re: PROBLEM: BUG when using memory.kmem.limit_in_bytes Message-ID: <20160122144854.GA14432@cmpxchg.org> References: <20160122135042.GF26192@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160122135042.GF26192@esperanza> Sender: owner-linux-mm@kvack.org List-ID: To: Vladimir Davydov Cc: Brian Christiansen , Michal Hocko , cgroups@vger.kernel.org, linux-mm@kvack.org 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@vger.kernel.org/msg1056544.html -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org