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

[Yong Zhang]

On Thu, Feb 17, 2011 at 10:03 AM, David Miller <davem@xxxxxxxxxxxxx> wrote:
> From: Yong Zhang <yong.zhang0@xxxxxxxxx>
> Date: Thu, 17 Feb 2011 09:37:30 +0800
>
>> On Tue, Feb 15, 2011 at 10:42 PM, Daniel Lezcano <daniel.lezcano@xxxxxxx> 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> Â[<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.

Thanks,
Yong

-- 
Only stand for myself
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