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SubjectRe: [PATCH 1/2] PF_DEAD: cleanup usage

* Oleg Nesterov <oleg@tv-sign.ru> wrote:

> schedule() checks PF_DEAD on every context switch, and sets ->state =
> EXIT_DEAD to ensure that exited task will be deactivated.
>
> I think it is better to set EXIT_DEAD in do_exit(), along with PF_DEAD
> flag.

nice idea - your patch looks good to me.

> It is safe to do without task_rq() locking, because concurrent
> try_to_wake_up() can't change task's ->state: the 'state' argument of
> try_to_wake_up() can't have EXIT_DEAD bit. And in case when
> try_to_wake_up() sees stale value of ->state == TASK_RUNNING it will
> do nothing.

we should really not be getting concurrent wakeups in this situation
anyway - and you are right that even if we got, it should have no effect
neither in the EXIT_DEAD nor in the TASK_RUNNING case.

Acked-by: Ingo Molnar <mingo@elte.hu>

Ingo
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