linux-kernel - Re: sched: circular dependency between sched_domains_mutex and oom_notify

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Date:	Mon, 18 Feb 2013 09:26:39 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Sasha Levin <sasha.levin@...cle.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Dave Jones <davej@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: sched: circular dependency between sched_domains_mutex and
 oom_notify_list


* Sasha Levin <sasha.levin@...cle.com> wrote:

> I suspect it's the result of adding the new rcu_oom_notify, but that happened
> about half a year ago so I'm not sure why this showed up only now.
> 
> [ 1039.634183] ======================================================
> [ 1039.635717] [ INFO: possible circular locking dependency detected ]
> [ 1039.637255] 3.8.0-rc7-next-20130215-sasha-00003-gea816fa #286 Tainted: G        W
> [ 1039.639104] -------------------------------------------------------
> [ 1039.640579] init/1 is trying to acquire lock:
> [ 1039.641224]  ((oom_notify_list).rwsem){.+.+..}, at: [<ffffffff81141c8f>] __blocking_notifier_call_chain+0x7f/0xc0

We changed (optimized) rwsems via:

 3a15e0e0cdda rwsem: Implement writer lock-stealing for better scalability

so maybe it can hit different codepaths and races now?

Thanks,

	Ingo
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