From: Michal Hocko <mhocko@suse.cz>
To: Johannes Weiner <jweiner@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
linux-mm@kvack.org, Balbir Singh <bsingharora@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [patch] memcg: pin execution to current cpu while draining stock
Date: Thu, 18 Aug 2011 07:56:49 +0200 [thread overview]
Message-ID: <20110818055649.GA23056@tiehlicka.suse.cz> (raw)
In-Reply-To: <20110817194927.GA10982@redhat.com>
On Wed 17-08-11 21:49:27, Johannes Weiner wrote:
> Commit d1a05b6 'memcg: do not try to drain per-cpu caches without
> pages' added a drain_local_stock() call to a preemptible section.
>
> The draining task looks up the cpu-local stock twice to set the
> draining-flag, then to drain the stock and clear the flag again. If
> the task is migrated to a different CPU in between, noone will clear
> the flag on the first stock and it will be forever undrainable. Its
> charge can not be recovered and the cgroup can not be deleted anymore.
>
> Properly pin the task to the executing CPU while draining stocks.
>
> Signed-off-by: Johannes Weiner <jweiner@redhat.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com
> Cc: Michal Hocko <mhocko@suse.cz>
My fault, I didn't realize that drain_local_stock needs preemption
disabled. Sorry about that and good work, Johannes.
Acked-by: Michal Hocko <mhocko@suse.cz>
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next prev parent reply other threads:[~2011-08-18 5:56 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-22 12:43 [PATCH 0/4 v2] memcg: cleanup per-cpu charge caches Michal Hocko
2011-07-21 7:38 ` [PATCH 1/4] memcg: do not try to drain per-cpu caches without pages Michal Hocko
2011-07-25 1:16 ` KAMEZAWA Hiroyuki
2011-08-17 19:49 ` [patch] memcg: pin execution to current cpu while draining stock Johannes Weiner
2011-08-18 0:24 ` KAMEZAWA Hiroyuki
2011-08-18 5:56 ` Michal Hocko [this message]
2011-07-22 10:24 ` [PATCH 2/4] memcg: unify sync and async per-cpu charge cache draining Michal Hocko
2011-07-22 10:27 ` [PATCH 3/4] memcg: add mem_cgroup_same_or_subtree helper Michal Hocko
2011-07-22 11:20 ` [PATCH 4/4] memcg: get rid of percpu_charge_mutex lock Michal Hocko
2011-07-25 1:18 ` KAMEZAWA Hiroyuki
2011-08-08 18:47 ` Johannes Weiner
2011-08-08 21:47 ` Michal Hocko
2011-08-08 23:19 ` Johannes Weiner
2011-08-09 7:26 ` Michal Hocko
2011-08-09 9:31 ` [PATCH RFC] memcg: fix drain_all_stock crash Michal Hocko
2011-08-09 9:32 ` KAMEZAWA Hiroyuki
2011-08-09 9:45 ` Michal Hocko
2011-08-09 9:53 ` KAMEZAWA Hiroyuki
2011-08-09 10:09 ` Michal Hocko
2011-08-09 10:07 ` KAMEZAWA Hiroyuki
2011-08-09 11:46 ` Michal Hocko
2011-08-09 23:54 ` KAMEZAWA Hiroyuki
2011-08-10 7:29 ` Michal Hocko
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