linux-next: spinlock lockup with next-20081118 on powerpc

[Stephen Rothwell]

Hi Jens,

On Wed, 19 Nov 2008 10:43:00 +0100 Jens Axboe <jens.axboe at oracle.com> wrote:
>
> On Wed, Nov 19 2008, Stephen Rothwell wrote:
> > 
> > Unable to handle kernel paging request for data at address 0x00000000
> > Faulting instruction address: 0xc000000000503030
> > cpu 0x0: Vector: 300 (Data Access) at [c00000000ffffa40]
> >     pc: c000000000503030: ._spin_lock_irqsave+0x40/0x110
> >     lr: c0000000002571f8: .blk_rq_timed_out_timer+0x48/0x190
> >     sp: c00000000ffffcc0
> >    msr: 8000000000009032
> >    dar: 0
> >  dsisr: 40000000
> >   current = 0xc000000022d31040
> >   paca    = 0xc000000000897300
> >     pid   = 3399, comm = ckbcomp
> > enter ? for help
> > [c00000000ffffd50] c0000000002571f8 .blk_rq_timed_out_timer+0x48/0x190
> > [c00000000ffffe00] c00000000006c2f4 .run_timer_softirq+0x1c4/0x2a0
> > [c00000000ffffed0] c000000000065298 .__do_softirq+0xe8/0x1f0
> > [c00000000fffff90] c000000000029224 .call_do_softirq+0x14/0x24
> > [c000000022ad3c80] c00000000000d420 .do_softirq+0xf0/0x140
> > [c000000022ad3d20] c0000000000654a4 .irq_exit+0x74/0x90
> > [c000000022ad3da0] c000000000025844 .timer_interrupt+0x134/0x150
> > [c000000022ad3e30] c000000000003700 decrementer_common+0x100/0x180
> > --- Exception: 901 (Decrementer) at 000000000ff52440
> 
> That's even more weird, how could 'data' passed in to the timer ever be
> 0? It's setup like this:

'data' above is generic, not a variable name. The 0 is probably the
address of the spinlock (though I need to check more to be sure) as it
crashed inside _spin_lock_irqsave.

>         setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
> 
> when we allocate the queue. How did this trigger?

Not sure what you mean?
-- 
Cheers,
Stephen Rothwell                    sfr at canb.auug.org.au
http://www.canb.auug.org.au/~sfr/
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