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Subject: Re: net/rfkill: WARNING in rfkill_fop_read
From: Johannes Berg <johannes@sipsolutions.net>
To: Dmitry Vyukov <dvyukov@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        linux-wireless@vger.kernel.org, netdev <netdev@vger.kernel.org>,
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        =?ISO-8859-1?Q?Jo=E3o?= Paulo Rechi Vita <jprvita@gmail.com>
Cc: 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>
Date: Tue, 26 Jan 2016 11:08:08 +0100
In-Reply-To: <CACT4Y+a9pNis4UH3zV4PCD5DhY-wk1+eRU8s-SM2Bm5mjpPiOg@mail.gmail.com> (sfid-20160126_105528_655164_E24E3E9D)
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	 (sfid-20160126_105528_655164_E24E3E9D)
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On Tue, 2016-01-26 at 10:55 +0100, Dmitry Vyukov wrote:
> Hello,
> 
> The following program triggers WARNING message in rfkill_fop_read:
> 
> ------------[ cut here ]------------
> WARNING: CPU: 2 PID: 6975 at kernel/sched/core.c:7663
> __might_sleep+0x138/0x1a0()
> do not call blocking ops when !TASK_RUNNING; state=1 set at
> [<ffffffff81436e01>] prepare_to_wait_event+0x141/0x410
> kernel/sched/wait.c:210

>  [<     inline     >] rfkill_readable net/rfkill/core.c:1102

Yeah, this should not acquire the mutex ... but luckily it's not a
problem not to anyway, so it's easy to fix. Thanks! I'll send out a fix
once I've tested it.

> // autogenerated by syzkaller (http://github.com/google/syzkaller)

gotta love the raw mmap etc. :)

johannes