linux-kernel - Re: [PATCH -v2 5/5] OOM, PM: make OOM detection in the freezer path raceless

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Message-ID: <20150108115124.GA6027@dhcp22.suse.cz>
Date:	Thu, 8 Jan 2015 12:51:24 +0100
From:	Michal Hocko <mhocko@...e.cz>
To:	linux-mm@...ck.org
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>,
	"\\\"Rafael J. Wysocki\\\"" <rjw@...ysocki.net>,
	David Rientjes <rientjes@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Cong Wang <xiyou.wangcong@...il.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-pm@...r.kernel.org
Subject: Re: [PATCH -v2 5/5] OOM, PM: make OOM detection in the freezer path
 raceless

On Fri 05-12-14 17:41:47, Michal Hocko wrote:
[...]
> +bool oom_killer_disable(void)
> +{
> +	/*
> +	 * Make sure to not race with an ongoing OOM killer
> +	 * and that the current is not the victim.
> +	 */
> +	down_write(&oom_sem);
> +	if (test_thread_flag(TIF_MEMDIE)) {
> +		up_write(&oom_sem);
> +		return false;
> +	}
> +
> +	oom_killer_disabled = true;
> +	up_write(&oom_sem);
> +
> +	wait_event(oom_victims_wait, atomic_read(&oom_victims));

Ups brainfart... Should be !atomic_read(&oom_victims). Condition says
for what we are waiting not when we are waiting.

> +
> +	return true;
> +}
[...]
-- 
Michal Hocko
SUSE Labs
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