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

[Daniel Lezcano]

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@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>    [<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

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