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Date: Mon, 18 Jun 2012 21:37:01 +0900
From: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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To: Glauber Costa <glommer@parallels.com>
CC: linux-mm@kvack.org, Pekka Enberg <penberg@kernel.org>,
        Cristoph Lameter <cl@linux.com>, David Rientjes <rientjes@google.com>,
        cgroups@vger.kernel.org, devel@openvz.org,
        linux-kernel@vger.kernel.org, Frederic Weisbecker <fweisbec@gmail.com>,
        Suleiman Souhlal <suleiman@google.com>,
        Pekka Enberg <penberg@cs.helsinki.fi>, Michal Hocko <mhocko@suse.cz>,
        Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH v4 23/25] memcg: propagate kmem limiting information to
 children
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(2012/06/18 19:28), Glauber Costa wrote:
> The current memcg slab cache management fails to present satisfatory hierarchical
> behavior in the following scenario:
> 
> ->  /cgroups/memory/A/B/C
> 
> * kmem limit set at A
> * A and B empty taskwise
> * bash in C does find /
> 
> Because kmem_accounted is a boolean that was not set for C, no accounting
> would be done. This is, however, not what we expect.
> 

Hmm....do we need this new routines even while we have mem_cgroup_iter() ?

Doesn't this work ?

	struct mem_cgroup {
		.....
		bool kmem_accounted_this;
		atomic_t kmem_accounted;
		....
	}

at set limit

	....set_limit(memcg) {

		if (newly accounted) {
			mem_cgroup_iter() {
				atomic_inc(&iter->kmem_accounted)
			}
		} else {
			mem_cgroup_iter() {
				atomic_dec(&iter->kmem_accounted);
			}
	}


hm ? Then, you can see kmem is accounted or not by atomic_read(&memcg->kmem_accounted);

Thanks,
-Kame