Re: WARNING: at kernel/lockdep.c:2323 trace_hardirqs_on_caller+0xb9/0x16c()

[Daniel Lezcano <daniel.lezcano@free.fr>]

On 02/17/2011 12:28 PM, Tejun Heo wrote:
> Hello,
>
> On Thu, Feb 17, 2011 at 10:43:57AM +0800, Yong Zhang wrote:
>> On Thu, Feb 17, 2011 at 10:03 AM, David Miller<davem@davemloft.net>  wrote:
>>> From: Yong Zhang<yong.zhang0@gmail.com>
>>> Date: Thu, 17 Feb 2011 09:37:30 +0800
>>>
>>>> On Tue, Feb 15, 2011 at 10:42 PM, Daniel Lezcano<daniel.lezcano@free.fr>  wrote:
>>>>> Hi All,
>>>>>
>>>>> I am running a 2.6.38-rc4-next-20110215+ kernel on qemu x86_64 and the
>>>>> following traces appear in the console:
>>>>>
>>>>> Feb 15 15:00:24 lucid kernel: ------------[ cut here ]------------
>>>>> Feb 15 15:00:24 lucid kernel: WARNING: at kernel/lockdep.c:2323
>>>>> trace_hardirqs_on_caller+0xb9/0x16c()
>>>>> Feb 15 15:00:24 lucid kernel: Hardware name: Bochs
>>>>> Feb 15 15:00:24 lucid kernel: Pid: 1477, comm: mountall Not tainted
>>>>> 2.6.38-rc4-next-20110215+ #74
>>>>> Feb 15 15:00:24 lucid kernel: Call Trace:
>>>>> Feb 15 15:00:24 lucid kernel:<IRQ>    [<ffffffff8102b8a5>] ?
>>>>> warn_slowpath_common+0x7b/0x93
>>>>> Feb 15 15:00:24 lucid kernel: [<ffffffff8146c097>] ?
>>>>> _raw_spin_unlock_irq+0x2b/0x30
>>>>> Feb 15 15:00:24 lucid kernel: [<ffffffff8102b8d2>] ?
>>>>> warn_slowpath_null+0x15/0x17
>>>>> Feb 15 15:00:24 lucid kernel: [<ffffffff8104f796>] ?
>>>>> trace_hardirqs_on_caller+0xb9/0x16c
>>>>> Feb 15 15:00:24 lucid kernel: [<ffffffff8104f856>] ?
>>>>> trace_hardirqs_on+0xd/0xf
>>>>> Feb 15 15:00:24 lucid kernel: [<ffffffff8146c097>] ?
>>>>> _raw_spin_unlock_irq+0x2b/0x30
>>>>> Feb 15 15:00:24 lucid kernel: [<ffffffff812e167e>] ?
>>>>> do_ide_request+0x32/0x590
>>>> Seems related to IDE SUBSYSTEM
>>> Which hasn't had any changes in the past release.
>> OK.
>>
>> Cc'ing Tejun Heo
>>
>> For the back trace, I think __blk_run_queue() is the ligament.
>> As from the comment of __blk_run_queue(), it must be called
>> with the queue lock and interrupts disabled. And the lock
>> is hold through spin_lock_irqsave(q->queue_lock, flags); at
>> blk_end_bidi_request().
>>
>> But in do_ide_request(), it realse the lock through
>> spin_unlock_irq(q->queue_lock); which make the state
>> inconsistent.
>>
>> BTW, do_ide_request() also say it might_sleep(), this warning
>> also trigger in Daniel's log.
> This seems to be the same problem Jan reported and fixed by the
> following patches.
>
>    http://article.gmane.org/gmane.linux.kernel/1101766/raw
>    http://article.gmane.org/gmane.linux.ide/48819/raw
>
> Can you please test whether these two patches fix the problem?

Thanks Tejun !

I applied these patches to linux-next and I blindly fixed some minors 
conflicts. AFAICT, the problem does no longer occur and it seems the 
patches fix the problem. I am not sure I resolved the conflict correctly 
as I know nothing about this subsystem. Shall I resend these patches for 
inclusion and you check they are correct ?

   -- Daniel