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From: Andrew Morton <akpm@linux-foundation.org>
To: Michal Hocko <mhocko@suse.cz>
Cc: linux-mm@kvack.org, Balbir Singh <bsingharora@gmail.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2 v2] memcg: make oom_lock 0 and 1 based rather than coutner
Date: Thu, 21 Jul 2011 13:58:17 -0700	[thread overview]
Message-ID: <20110721135817.baab2a2c.akpm@linux-foundation.org> (raw)
In-Reply-To: <44ec61829ed8a83b55dc90a7aebffdd82fe0e102.1310732789.git.mhocko@suse.cz>

On Wed, 13 Jul 2011 13:05:49 +0200
Michal Hocko <mhocko@suse.cz> wrote:

> @@ -1893,6 +1942,8 @@ bool mem_cgroup_handle_oom(struct mem_cgroup *mem, gfp_t mask)

does:

: 	memcg_wakeup_oom(mem);
: 	mutex_unlock(&memcg_oom_mutex);
: 
: 	mem_cgroup_unmark_under_oom(mem);
: 
: 	if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current))
: 		return false;
: 	/* Give chance to dying process */
: 	schedule_timeout(1);
: 	return true;
: }

Calling schedule_timeout() in state TASK_RUNNING is equivalent to
calling schedule() and then pointlessly wasting some CPU cycles.

Someone might want to take a look at that, and wonder why this bug
wasn't detected in testing ;)

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  reply	other threads:[~2011-07-21 20:58 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-07-15 12:26 [PATCH 0/2 v2 ] memcg: oom locking updates Michal Hocko
2011-07-13 11:05 ` [PATCH 1/2 v2] memcg: make oom_lock 0 and 1 based rather than coutner Michal Hocko
2011-07-21 20:58   ` Andrew Morton [this message]
2011-07-22  0:15     ` KAMEZAWA Hiroyuki
2011-08-09 14:03   ` Johannes Weiner
2011-08-09 15:22     ` Michal Hocko
2011-08-09 15:37       ` Johannes Weiner
2011-08-09 15:43         ` Michal Hocko
2011-08-10  0:22         ` KAMEZAWA Hiroyuki
2011-07-14 15:29 ` [PATCH 2/2] memcg: change memcg_oom_mutex to spinlock Michal Hocko
2011-07-20  5:55   ` KAMEZAWA Hiroyuki
2011-07-20  7:01     ` Michal Hocko
2011-07-20  6:34   ` Balbir Singh
2011-07-20  7:00     ` Michal Hocko

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