Re: [GIT PULL rcu/next] rcu commits for 2.6.40
From: Yinghai Lu
Date: Thu May 19 2011 - 17:46:13 EST
On 05/19/2011 02:15 PM, Frederic Weisbecker wrote:
> On Thu, May 19, 2011 at 12:51:26PM -0700, Yinghai Lu wrote:
>> [ 85.194797] <idle>-0 0d... 85152953us : rcu_irq_enter: 1 49
>> [ 85.194808] <idle>-0 0dN.. 85153081us : <stack trace>
>> [ 85.194809] => rcu_irq_exit
>> [ 85.194810] => irq_exit
>> [ 85.194811] => smp_apic_timer_interrupt
>> [ 85.194812] => apic_timer_interrupt
>> [ 85.194813] => cpu_idle
>> [ 85.194813] => rest_init
>> [ 85.194814] => start_kernel
>> [ 85.194815] => x86_64_start_reservations
> So it's the dynticks_nesting going crazy. As if we had rcu_irq_enter()
> without rcu_irq_exit().
> I see you have CONFIG_DEBUG_LOCKING_API_SELFTESTS=y
> and the locking api selftest is doing a strange thing: if we look
> at HARDIRQ_ENTER(), it calls irq_enter(), but HARDIRQ_EXIT() only
> calls __irq_exit(). Which means it lacks the rcu_irq_exit().
> So, if I understood correctly the thing there, some selftests simulating
> the hardirq context are unbalancing the rcu state.
> Does that help if you unset CONFIG_DEBUG_LOCKING_API_SELFTESTS ?
yes, after unset that, no warning and delay...
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