SMP soft lockup on smp_call_function_many when doing flush_tlb_page

[saeed bishara]

>
> Did you get a chance to try this patch?
yes, it works fine
>
>> >> An alternative would be to copy the cpumask to a local variable in
>> >> on_each_cpu_mask(), though the workaround above would cover other cases
>> >> that we haven't spotted yet. Also, the smp_call_function_many()
>> >> description doesn't state that the cpumask should not be modified.
>> >>
>> >>
>> >> diff --git a/arch/arm/kernel/smp_tlb.c b/arch/arm/kernel/smp_tlb.c
>> >> index 8f57f32..1717dec 100644
>> >> --- a/arch/arm/kernel/smp_tlb.c
>> >> +++ b/arch/arm/kernel/smp_tlb.c
>> >> @@ -16,10 +16,13 @@
>> >>  static void on_each_cpu_mask(void (*func)(void *), void *info, int wait,
>> >>        const struct cpumask *mask)
>> >>  {
>> >> +       struct cpumask call_mask;
>> >> +
>> >>        preempt_disable();
>> >>
>> >> +       cpumask_copy(&call_mask, mask);
>> >>        smp_call_function_many(mask, func, info, wait);
>> >  I'll check this one, but the mask here should be call_mask.
>> >> -       if (cpumask_test_cpu(smp_processor_id(), mask))
>> >> +       if (cpumask_test_cpu(smp_processor_id(), &call_mask))
>> >>                func(info);
>> >>
>> this patch increases my system instability, for some reason, the
>> call_function_data data get corrupted when the
>> generic_smp_call_function_interrupt() is running.
>
> Strange, the patch only copies the cpumask.
this patch also works fine, seems the instability was due to the code
that I added in order to accelerate the failure.

saeed