Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755464Ab2FTNUy (ORCPT ); Wed, 20 Jun 2012 09:20:54 -0400 Received: from cantor2.suse.de ([195.135.220.15]:48610 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753790Ab2FTNUw (ORCPT ); Wed, 20 Jun 2012 09:20:52 -0400 Date: Wed, 20 Jun 2012 15:20:50 +0200 From: Michal Hocko To: Glauber Costa Cc: linux-mm@kvack.org, Pekka Enberg , Cristoph Lameter , David Rientjes , cgroups@vger.kernel.org, devel@openvz.org, kamezawa.hiroyu@jp.fujitsu.com, linux-kernel@vger.kernel.org, Frederic Weisbecker , Suleiman Souhlal , Tejun Heo , Li Zefan , Johannes Weiner Subject: Re: [PATCH v4 05/25] memcg: Always free struct memcg through schedule_work() Message-ID: <20120620132050.GE5541@tiehlicka.suse.cz> References: <1340015298-14133-1-git-send-email-glommer@parallels.com> <1340015298-14133-6-git-send-email-glommer@parallels.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1340015298-14133-6-git-send-email-glommer@parallels.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: 3686 Lines: 107 On Mon 18-06-12 14:27:58, Glauber Costa wrote: > Right now we free struct memcg with kfree right after a > rcu grace period, but defer it if we need to use vfree() to get > rid of that memory area. We do that by need, because we need vfree > to be called in a process context. > > This patch unifies this behavior, by ensuring that even kfree will > happen in a separate thread. The goal is to have a stable place to > call the upcoming jump label destruction function outside the realm > of the complicated and quite far-reaching cgroup lock (that can't be > held when calling neither the cpu_hotplug.lock nor the jump_label_mutex) This one is in memcg-devel (mmotm) tree for quite some time with acks from me and Kamezawa. > Signed-off-by: Glauber Costa > CC: Tejun Heo > CC: Li Zefan > CC: Kamezawa Hiroyuki > CC: Johannes Weiner > CC: Michal Hocko > --- > mm/memcontrol.c | 24 +++++++++++++----------- > 1 file changed, 13 insertions(+), 11 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index e3b528e..ce15be4 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -245,8 +245,8 @@ struct mem_cgroup { > */ > struct rcu_head rcu_freeing; > /* > - * But when using vfree(), that cannot be done at > - * interrupt time, so we must then queue the work. > + * We also need some space for a worker in deferred freeing. > + * By the time we call it, rcu_freeing is not longer in use. > */ > struct work_struct work_freeing; > }; > @@ -4826,23 +4826,28 @@ out_free: > } > > /* > - * Helpers for freeing a vzalloc()ed mem_cgroup by RCU, > + * Helpers for freeing a kmalloc()ed/vzalloc()ed mem_cgroup by RCU, > * but in process context. The work_freeing structure is overlaid > * on the rcu_freeing structure, which itself is overlaid on memsw. > */ > -static void vfree_work(struct work_struct *work) > +static void free_work(struct work_struct *work) > { > struct mem_cgroup *memcg; > + int size = sizeof(struct mem_cgroup); > > memcg = container_of(work, struct mem_cgroup, work_freeing); > - vfree(memcg); > + if (size < PAGE_SIZE) > + kfree(memcg); > + else > + vfree(memcg); > } > -static void vfree_rcu(struct rcu_head *rcu_head) > + > +static void free_rcu(struct rcu_head *rcu_head) > { > struct mem_cgroup *memcg; > > memcg = container_of(rcu_head, struct mem_cgroup, rcu_freeing); > - INIT_WORK(&memcg->work_freeing, vfree_work); > + INIT_WORK(&memcg->work_freeing, free_work); > schedule_work(&memcg->work_freeing); > } > > @@ -4868,10 +4873,7 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg) > free_mem_cgroup_per_zone_info(memcg, node); > > free_percpu(memcg->stat); > - if (sizeof(struct mem_cgroup) < PAGE_SIZE) > - kfree_rcu(memcg, rcu_freeing); > - else > - call_rcu(&memcg->rcu_freeing, vfree_rcu); > + call_rcu(&memcg->rcu_freeing, free_rcu); > } > > static void mem_cgroup_get(struct mem_cgroup *memcg) > -- > 1.7.10.2 > > -- > 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/ -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- 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/