Re: spinlock lockup on CPU#0

Justin Mattock
2008-04-26T18:39:18Z

On Sat, Apr 26, 2008 at 6:29 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
>
> On Thu, 24 Apr 2008 01:41:32 +0000 "Justin Mattock" <justinmattock@gmail.com> wrote:
>
> > Hello, I recorded a .mov of a spinlock, but cant seem to send it out,
> > so I have to manually write it down:
> >
> > BUG: spinlock lockup on CPU#0, swapper/0, c17fa6c0
> > Pid: 0. swapper Not tainted 2.6.25-03562-g3dc5063 #1
> > [<c0219fbb>] _raw_spin_lock+0xd5/0xf9
> > [<c0377c6b>] _spin_lock+0x8/0xa
> > [<c011cdce>] task_rq_lock+0x44/0x6b
> > [<c011cfb4>] try_to_wake+0x2a/0x1c4
> > [<co11d159>] default_wake_function+0xb/0xd
> > [<co118847>] __wake_up_common+0x2f/0x5a
> > [<c011bc11>] complete+0x2b/0x3e
> > [<c02ad79a>] usb_api_blocking_completion+0x13/0x15
> > [<c02abadc>] usb_hcd_giveback_urb+0x52/0x82
> > [<f88686c7>] ehci_urb_done+0x6f/0x7c [ehci_hcd]
> > [<f8869614>] qh_completions+0x2d7/0x348 [ehci_hcd]
> > [<f8869721>] ehci_work+0x9c [ehci_hcd]
> > [<c0107c35>] ? sched_clock+0xb/0x1c
> > [<c0119bec>] ? __update_rq_clock+0x94/0x15a
> > [<f886c827>] ehci_irq+0x138/0x15f [ehci_hcd]
> > [<c02abd9> ] usb_hcd_irq+0x23/0x51
> > [<c0151c43>] handle_IRQ_event+0x2a/0x5a
> > [<c0152d2c>] handle_fasteoi_irq+0x74/0xb6
> > [<c01058c5>] do_IRQ+0x71/0x8c
> > [<c01042f7>] common_interrupt+0x23/0x28
> > [<c011fb07>] ? sched_clock_idle_wakeup_event+0x5b/0x74
> > [<c02cc212>] acpi_idle_enter_bm+0x2a4/0x31f [processor]
> > [<c02cc212>] cpuidle_idle_call+0x5c/0x8c
> > [<c02cc1b4>] ? cpuidle_idle_call+0x0/0x8c
> > [<c0102571>] cpu_idle+0xb1/0xd1
> > [<c036b371>] reset_init+0x49/0x4b
> > =====================================================
> >
> >
> > Hopefully the numbers are right, and hopefully this provides enough
> > info to help the kernel out
>
> Well that's cute. At a guess I'd say that acpi_processor_idle() managed to
> call sched_clock_idle_wakeup_event() with local interrupts enabled. We
> took an interrupt with rq->lock held and things went downhill from there.
>
> Can you add this please, see if it triggers?
>
>
> --- a/kernel/sched.c~a
> +++ a/kernel/sched.c
> @@ -811,6 +811,7 @@ void sched_clock_idle_sleep_event(void)
> {
> struct rq *rq = cpu_rq(smp_processor_id());
>
> + WARN_ON(!irqs_disabled());
> spin_lock(&rq->lock);
> __update_rq_clock(rq);
> spin_unlock(&rq->lock);
> @@ -826,6 +827,7 @@ void sched_clock_idle_wakeup_event(u64 d
> struct rq *rq = cpu_rq(smp_processor_id());
> u64 now = sched_clock();
>
> + WARN_ON(!irqs_disabled());
> rq->idle_clock += delta_ns;
> /*
> * Override the previous timestamp and ignore all
> _
>
>

Yeah, I dont mind adding this to see what happens.
regards

--
Justin P. Mattock