Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759539Ab3DDMAy (ORCPT ); Thu, 4 Apr 2013 08:00:54 -0400 Received: from cantor2.suse.de ([195.135.220.15]:36496 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759515Ab3DDMAx (ORCPT ); Thu, 4 Apr 2013 08:00:53 -0400 Date: Thu, 4 Apr 2013 14:00:49 +0200 From: Michal Hocko To: Li Zefan Cc: linux-mm@kvack.org, LKML , Cgroups , Tejun Heo , Glauber Costa , KAMEZAWA Hiroyuki , Johannes Weiner Subject: Re: [RFC][PATCH 0/7] memcg: make memcg's life cycle the same as cgroup Message-ID: <20130404120049.GI29911@dhcp22.suse.cz> References: <515BF233.6070308@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <515BF233.6070308@huawei.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2043 Lines: 47 On Wed 03-04-13 17:11:15, Li Zefan wrote: > (I'll be off from my office soon, and I won't be responsive in the following > 3 days.) > > I'm working on converting memcg to use cgroup->id, and then we can kill css_id. > > Now memcg has its own refcnt, so when a cgroup is destroyed, the memcg can > still be alive. This patchset converts memcg to always use css_get/put, so > memcg will have the same life cycle as its corresponding cgroup, and then > it's always safe for memcg to use cgroup->id. > > The historical reason that memcg didn't use css_get in some cases, is that > cgroup couldn't be removed if there're still css refs. The situation has > changed so that rmdir a cgroup will succeed regardless css refs, but won't > be freed until css refs goes down to 0. > > This is an early post, and it's NOT TESTED. I just want to see if the changes > are fine in general. yes, I like the approach and it looks correct as well (some minor things mentioned in the patches). Thanks a lot Li! This will make our lifes much easier. The separate ref counting was PITA especially after introduction of kmem accounting which made its usage even more trickier. > btw, after this patchset I think we don't need to free memcg via RCU, because > cgroup is already freed in RCU callback. But this depends on changes waiting in for-3.10 branch, right? Anyway, I think we should be safe with the workqueue based releasing as well once mem_cgroup_{get,put} are gone, right? > Note this patchset is based on a few memcg fixes I sent (but hasn't been > accepted) > > -- > kernel/cgroup.c | 10 ++++++++ > mm/memcontrol.c | 129 ++++++++++++++++++++++++++++++++++++++------------------------------------------------------- > 2 files changed, 62 insertions(+), 77 deletions(-) -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/