From: Glauber Costa <glommer@parallels.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@suse.de>,
Suleiman Souhlal <suleiman@google.com>, Tejun Heo <tj@kernel.org>,
cgroups@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com,
Johannes Weiner <hannes@cmpxchg.org>,
Greg Thelen <gthelen@google.com>,
devel@openvz.org, Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: [PATCH v4 08/14] res_counter: return amount of charges after res_counter_uncharge
Date: Tue, 9 Oct 2012 19:14:57 +0400 [thread overview]
Message-ID: <50743F71.7090409@parallels.com> (raw)
In-Reply-To: <20121009150845.GC7655@dhcp22.suse.cz>
On 10/09/2012 07:08 PM, Michal Hocko wrote:
> As I have already mentioned in my previous feedback this is cetainly not
> atomic as you the lock protects only one group in the hierarchy. How is
> the return value from this function supposed to be used?
So, I tried to make that clearer in the updated changelog.
Only the value of the base memcg (the one passed to the function) is
returned, and it is atomic, in the sense that it has the same semantics
as the atomic variables: If 2 threads uncharge 4k each from a 8 k
counter, a subsequent read can return 0 for both. The return value here
will guarantee that only one sees the drop to 0.
This is used in the patch "kmem_accounting lifecycle management" to be
sure that only one process will call mem_cgroup_put() in the memcg
structure.
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next prev parent reply other threads:[~2012-10-09 15:15 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-08 10:06 [PATCH v4 00/14] kmem controller for memcg Glauber Costa
2012-10-08 10:06 ` [PATCH v4 01/14] memcg: Make it possible to use the stock for more than one page Glauber Costa
2012-10-08 10:06 ` [PATCH v4 02/14] memcg: Reclaim when more than one page needed Glauber Costa
2012-10-16 3:22 ` Kamezawa Hiroyuki
2012-10-08 10:06 ` [PATCH v4 03/14] memcg: change defines to an enum Glauber Costa
2012-10-08 10:06 ` [PATCH v4 04/14] kmem accounting basic infrastructure Glauber Costa
2012-10-11 10:11 ` Michal Hocko
2012-10-11 12:53 ` Michal Hocko
2012-10-11 13:38 ` Michal Hocko
2012-10-12 7:36 ` Glauber Costa
2012-10-12 8:27 ` Michal Hocko
2012-10-08 10:06 ` [PATCH v4 05/14] Add a __GFP_KMEMCG flag Glauber Costa
2012-10-09 15:04 ` Michal Hocko
2012-10-08 10:06 ` [PATCH v4 06/14] memcg: kmem controller infrastructure Glauber Costa
2012-10-11 12:42 ` Michal Hocko
2012-10-11 12:56 ` Michal Hocko
2012-10-12 7:45 ` Glauber Costa
2012-10-12 8:39 ` Michal Hocko
2012-10-12 8:44 ` Glauber Costa
2012-10-12 8:57 ` Michal Hocko
2012-10-12 9:13 ` Glauber Costa
2012-10-12 9:47 ` Michal Hocko
2012-10-16 8:00 ` Kamezawa Hiroyuki
2012-10-08 10:06 ` [PATCH v4 07/14] mm: Allocate kernel pages to the right memcg Glauber Costa
2012-10-08 10:06 ` [PATCH v4 08/14] res_counter: return amount of charges after res_counter_uncharge Glauber Costa
2012-10-09 15:08 ` Michal Hocko
2012-10-09 15:14 ` Glauber Costa [this message]
2012-10-09 15:35 ` Michal Hocko
2012-10-10 9:03 ` Glauber Costa
2012-10-10 11:24 ` Michal Hocko
2012-10-10 11:25 ` Michal Hocko
2012-10-16 8:20 ` Kamezawa Hiroyuki
2012-10-08 10:06 ` [PATCH v4 09/14] memcg: kmem accounting lifecycle management Glauber Costa
2012-10-11 13:11 ` Michal Hocko
2012-10-12 7:47 ` Glauber Costa
2012-10-12 8:41 ` Michal Hocko
2012-10-16 8:41 ` Kamezawa Hiroyuki
2012-10-08 10:06 ` [PATCH v4 10/14] memcg: use static branches when code not in use Glauber Costa
2012-10-11 13:40 ` Michal Hocko
2012-10-12 7:47 ` Glauber Costa
2012-10-16 8:48 ` Kamezawa Hiroyuki
2012-10-08 10:06 ` [PATCH v4 11/14] memcg: allow a memcg with kmem charges to be destructed Glauber Costa
2012-10-08 10:06 ` [PATCH v4 12/14] execute the whole memcg freeing in free_worker Glauber Costa
2012-10-11 14:21 ` Michal Hocko
2012-10-08 10:06 ` [PATCH v4 13/14] protect architectures where THREAD_SIZE >= PAGE_SIZE against fork bombs Glauber Costa
2012-10-08 10:06 ` [PATCH v4 14/14] Add documentation about the kmem controller Glauber Costa
2012-10-11 14:35 ` Michal Hocko
2012-10-12 7:53 ` Glauber Costa
2012-10-12 8:44 ` Michal Hocko
2012-10-17 7:29 ` Kamezawa Hiroyuki
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