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From: Tejun Heo <tj@kernel.org>
To: Ben Greear <greearb@candelatech.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: ath5k/mac80211:  Reproducible deadlock with 64-stations.
Date: Fri, 12 Nov 2010 11:15:45 +0100	[thread overview]
Message-ID: <4CDD13D1.9070608@kernel.org> (raw)
In-Reply-To: <4CDD12BD.7030208@kernel.org>

Just a bit of addition.

On 11/12/2010 11:11 AM, Tejun Heo wrote:
> It depends on what the work being flushed was doing.  Which one is it
> trying to flush?  Also, if the memory pressure is high enough, due to
> the dynamic nature of workqueue, processing of works can be delayed
> while trying to create new workers to process them.

Please note that under those circumstances, what's guaranteed is
forward-progress for workqueues which are used during memory reclaim.
Continuously scheduling works which will in turn pile up on rtnl_lock
is akin to constantly allocating memory while something holding
rtnl_lock is blocked due to memory pressure.  Correctness-wise, it
isn't necessarily deadlock but the only possible recourse is OOM.

Thanks.

-- 
tejun

  reply	other threads:[~2010-11-12 10:15 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-10 23:02 ath5k/mac80211: Reproducible deadlock with 64-stations Ben Greear
2010-11-11  0:57 ` Ben Greear
2010-11-11  1:03   ` Johannes Berg
2010-11-11  5:51     ` Ben Greear
2010-11-11  1:02 ` Johannes Berg
2010-11-11  9:27   ` Tejun Heo
2010-11-11 16:55     ` Ben Greear
2010-11-11 18:26       ` Ben Greear
2010-11-11 23:12         ` Ben Greear
2010-11-12 10:11           ` Tejun Heo
2010-11-12 10:15             ` Tejun Heo [this message]
2010-11-12 18:06               ` Ben Greear
2010-11-12 18:13                 ` Tejun Heo
2010-11-12 18:34                   ` Ben Greear
2010-11-12 17:18             ` Ben Greear
2010-11-12  0:48       ` Ben Greear
2010-11-12  2:37         ` Johannes Berg
2010-11-12 16:32           ` Ben Greear
2010-11-12 16:45             ` Johannes Berg
2010-11-12 17:37               ` Ben Greear

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