Re: Q: a bogus task_running() check in try_to_wake_up() ?

[Ingo Molnar]

* Oleg Nesterov <oleg@xxxxxxxxxx> wrote:

> try_to_wake_up:
> 	
> 	if (p->se.on_rq)
> 		goto out_running;
> 
> 	...
> 
> 	if (unlikely(task_running(rq, p)))
> 		goto out_activate;
> 
> How it possible that rq->curr has on_rq == 0 ?
> 
> AFAICS, this can only happen if this task is rq->idle. But idle 
> threads should not sleep, we have a special "scheduling from the idle 
> thread!" check in schedule().

it's also possible if an arch uses __ARCH_WANT_INTERRUPTS_ON_CTXSW, 
right?

[ btw., we dont have a special "scheduling from the idle thread" check
  in schedule() anymore, it's now in kernel/sched_idletask.c :-) ]

	Ingo
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