From: Michal Hocko <mhocko@suse.cz>
To: Glauber Costa <glommer@parallels.com>
Cc: cgroups@vger.kernel.org, linux-mm@kvack.org,
Tejun Heo <tj@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>,
kamezawa.hiroyu@jp.fujitsu.com
Subject: Re: [PATCH v3 4/6] memcg: replace cgroup_lock with memcg specific memcg_lock
Date: Mon, 21 Jan 2013 18:37:31 +0100 [thread overview]
Message-ID: <20130121173729.GA24410@dhcp22.suse.cz> (raw)
In-Reply-To: <20130121163349.GR7798@dhcp22.suse.cz>
On Mon 21-01-13 17:33:49, Michal Hocko wrote:
> On Mon 21-01-13 20:12:17, Glauber Costa wrote:
> > On 01/21/2013 08:07 PM, Michal Hocko wrote:
> > >> > And the reason why kmemcg holds the set_limit mutex
> > >> > is just to protect from itself, then there is no *need* to hold any
> > >> > extra lock (and we'll never be able to stop holding the creation lock,
> > >> > whatever it is). So my main point here is not memcg_mutex vs
> > >> > set_limit_mutex, but rather, memcg_mutex is needed anyway, and once it
> > >> > is taken, the set_limit_mutex *can* be held, but doesn't need to.
> > > So you can update kmem specific usage of set_limit_mutex.
> > Meaning ?
>
> I thought you've said it is not needed and the code says that:
> - memcg_propagate_kmem is called with memcg_mutex held in css_alloc
> - memcg_update_kmem_limit takes both of them
> - kmem_cache_destroy_memcg_children _doesn't_ take both
>
> So one obvious way to go would be changing
> kmem_cache_destroy_memcg_children to memcg_mutex and removing
> set_limit_mutex from other two paths.
>
> This would leave set_limit_mutex lock for its original intention.
And then we could use a more suitable name: memcg_create_lock
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2013-01-21 17:37 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-21 11:13 [PATCH v3 0/6] replace cgroup_lock with memcg specific locking Glauber Costa
2013-01-21 11:13 ` [PATCH v3 1/6] memcg: prevent changes to move_charge_at_immigrate during task attach Glauber Costa
2013-01-21 11:13 ` [PATCH v3 2/6] memcg: split part of memcg creation to css_online Glauber Costa
2013-01-21 13:56 ` Michal Hocko
2013-01-21 11:13 ` [PATCH v3 3/6] memcg: fast hierarchy-aware child test Glauber Costa
2013-01-21 14:10 ` Michal Hocko
2013-01-21 11:13 ` [PATCH v3 4/6] memcg: replace cgroup_lock with memcg specific memcg_lock Glauber Costa
2013-01-21 14:49 ` Michal Hocko
2013-01-21 15:12 ` Glauber Costa
2013-01-21 15:20 ` Michal Hocko
2013-01-21 15:34 ` Glauber Costa
2013-01-21 16:07 ` Michal Hocko
2013-01-21 16:12 ` Glauber Costa
2013-01-21 16:33 ` Michal Hocko
2013-01-21 17:37 ` Michal Hocko [this message]
2013-01-21 11:13 ` [PATCH v3 5/6] memcg: increment static branch right after limit set Glauber Costa
2013-01-21 11:13 ` [PATCH v3 6/6] memcg: avoid dangling reference count in creation failure Glauber Costa
2013-01-21 12:30 ` Michal Hocko
2013-01-21 13:08 ` Glauber Costa
2013-01-21 13:19 ` Michal Hocko
2013-01-21 13:26 ` Glauber Costa
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