From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx126.postini.com [74.125.245.126]) by kanga.kvack.org (Postfix) with SMTP id 7BE2C6B004D for ; Tue, 4 Dec 2012 07:54:47 -0500 (EST) Date: Tue, 4 Dec 2012 13:54:45 +0100 From: Michal Hocko Subject: Re: [RFC PATCH 3/3] memcg: allocate pages for swap cgroup until the first child memcg is alive Message-ID: <20121204125445.GC1343@dhcp22.suse.cz> References: <50BDB5E0.7030906@oracle.com> <50BDB601.4090205@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50BDB601.4090205@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: Jeff Liu Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, Glauber Costa On Tue 04-12-12 16:36:17, Jeff Liu wrote: > - Call swap_cgroup_init() when the first child memcg was created. > - Free pages from swap cgroup once the latest child memcg was removed. This should be a separate patch > - Teach swap_cgroup_record()/swap_cgroup_cmpxchg()/swap_cgroup_lookup_id() > to aware of the new static variable. i.e, swap_cgroup_initialized, so that > they would not perform further jobs if swap cgroup is not active. This should be a preparatory patch. > > Signed-off-by: Jie Liu > CC: Glauber Costa > CC: Michal Hocko > CC: Kamezawa Hiroyuki > CC: Johannes Weiner > CC: Mel Gorman > CC: Andrew Morton > --- > mm/memcontrol.c | 3 +++ > mm/page_cgroup.c | 9 +++++++++ > 2 files changed, 12 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index dd39ba0..1f14375 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -4982,6 +4982,8 @@ mem_cgroup_create(struct cgroup *cont) > } > hotcpu_notifier(memcg_cpu_hotplug_callback, 0); > } else { > + if (swap_cgroup_init()) > + goto free_out; > parent = mem_cgroup_from_cont(cont->parent); > memcg->use_hierarchy = parent->use_hierarchy; > memcg->oom_kill_disable = parent->oom_kill_disable; > @@ -5046,6 +5048,7 @@ static void mem_cgroup_destroy(struct cgroup *cont) > struct mem_cgroup *memcg = mem_cgroup_from_cont(cont); > > kmem_cgroup_destroy(memcg); > + swap_cgroup_destroy(); > > mem_cgroup_put(memcg); > } > diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c > index f1b257b..63c6789 100644 > --- a/mm/page_cgroup.c > +++ b/mm/page_cgroup.c > @@ -429,6 +429,9 @@ unsigned short swap_cgroup_cmpxchg(swp_entry_t ent, > unsigned long flags; > unsigned short retval; > > + if (!atomic_read(&swap_cgroup_initialized)) > + return 0; > + > sc = lookup_swap_cgroup(ent, &ctrl); > > spin_lock_irqsave(&ctrl->lock, flags); > @@ -456,6 +459,9 @@ unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) > unsigned short old; > unsigned long flags; > > + if (!atomic_read(&swap_cgroup_initialized)) > + return 0; > + > sc = lookup_swap_cgroup(ent, &ctrl); > > spin_lock_irqsave(&ctrl->lock, flags); > @@ -474,6 +480,9 @@ unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) > */ > unsigned short lookup_swap_cgroup_id(swp_entry_t ent) > { > + if (!atomic_read(&swap_cgroup_initialized)) > + return 0; > + > return lookup_swap_cgroup(ent, NULL)->id; I think that the swap_cgroup_initialized test should be stuffed into lookup_swap_cgroup because it would be less fragile. -- Michal Hocko SUSE Labs -- 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