Re: BUG: using smp_processor_id() in preemptible [00000000] code:asm/8267

[Joerg Roedel]

On Tue, Mar 26, 2013 at 07:34:52PM +0100, Borislav Petkov wrote:
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 7b4a55d41efc..f3bb3384a106 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -4455,8 +4455,11 @@ static void perf_event_task_event(struct perf_task_event *task_event)
>  next:
>  		put_cpu_ptr(pmu->pmu_cpu_context);
>  	}
> +
> +	preempt_disable();
>  	if (task_event->task_ctx)
>  		perf_event_task_ctx(task_event->task_ctx, task_event);
> +	preempt_enable();
>  
>  	rcu_read_unlock();
>  }

What makes me wonder here is that the code is preemptible in an
rcu_read_locked section. As far as I know preemption needs to be
disabled while holding the rcu_read_lock().


	Joerg


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