linux-kernel - Re: net/bluetooth: workqueue destruction WARNING in hci_unregister

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Message-ID: <56D7FFE1.90900@suse.cz>
Date:	Thu, 3 Mar 2016 10:12:01 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	Tejun Heo <tj@...nel.org>
Cc:	Dmitry Vyukov <dvyukov@...gle.com>,
	Marcel Holtmann <marcel@...tmann.org>,
	Gustavo Padovan <gustavo@...ovan.org>,
	Johan Hedberg <johan.hedberg@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	linux-bluetooth@...r.kernel.org, netdev <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	syzkaller <syzkaller@...glegroups.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Takashi Iwai <tiwai@...e.com>
Subject: Re: net/bluetooth: workqueue destruction WARNING in
 hci_unregister_dev

Hi,

On 03/02/2016, 04:45 PM, Tejun Heo wrote:
> On Fri, Feb 19, 2016 at 01:10:00PM +0100, Jiri Slaby wrote:
>>> 1. didn't help, the problem persists. So I haven't applied the patch from 2.
>>
>> FWIW I dumped more info about the wq:
>> wq->name='hci0' pwq=ffff8800390d7600 wq->dfl_pwq=ffff8800390d5200
>> pwq->refcnt=2 pwq->nr_active=0 delayed_works: <nothing>
> 
> Can you please print out the same info for all pwq's during shutdown?
> It looks like we're leaking pwq refcnt but I can't spot a place where
> that could happen on an empty pwq.

I have not done that yet, but today, I see:
destroy_workqueue: name='req_hci0' pwq=ffff88002f590300
wq->dfl_pwq=ffff88002f591e00 pwq->refcnt=2 pwq->nr_active=0 delayed_works:
   pwq 12: cpus=0-1 node=0 flags=0x4 nice=-20 active=0/1
     in-flight: 18568:wq_barrier_func

thanks,
-- 
js
suse labs