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Subject: Re: net/bluetooth: workqueue destruction WARNING in
 hci_unregister_dev
To: Tejun Heo <tj@kernel.org>, Dmitry Vyukov <dvyukov@google.com>
References: <CACT4Y+ax7zMOxe+kd4tw5Xdbvt=qPdBhXGO0j7qJwdn5tsfNNg@mail.gmail.com>
 <56C5CE85.6090808@suse.cz>
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 <20160218174427.GG13177@mtj.duckdns.org> <56C6EC62.8080107@suse.cz>
Cc: Marcel Holtmann <marcel@holtmann.org>,
        Gustavo Padovan <gustavo@padovan.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        linux-bluetooth@vger.kernel.org, netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        syzkaller <syzkaller@googlegroups.com>,
        Kostya Serebryany <kcc@google.com>,
        Alexander Potapenko <glider@google.com>,
        Sasha Levin <sasha.levin@oracle.com>,
        Eric Dumazet <edumazet@google.com>, Takashi Iwai <tiwai@suse.com>
From: Jiri Slaby <jslaby@suse.cz>
Message-ID: <56C70618.3010902@suse.cz>
Date: Fri, 19 Feb 2016 13:10:00 +0100
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On 02/19/2016, 11:20 AM, Jiri Slaby wrote:
> On 02/18/2016, 06:44 PM, Tejun Heo wrote:
>> Hello,
>>
>> Can you please do the followings?
>>
>> 1. Remove WQ_MEM_RECLAIM from the affected workqueue and see whether
>>    the problem is reproducible.  WQ_MEM_RECLAIM on anything bluetooth
>>    doesn't make sense btw.  Why is it there?
>>
>> 2. If WQ_MEM_RECLAIM makes the issue go away, see whether the attached
>>    patch works too.
> 
> Hello,
> 
> 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>

> thanks,
-- 
js
suse labs