Re: [RFC/RFT PATCH v3] sched: automated per tty task groups

[Oleg Nesterov]

I didn't read this patch carefully (yet) but,

On 11/11, Mike Galbraith wrote:
>
> @@ -2569,6 +2576,7 @@ void sched_fork(struct task_struct *p, i
>  	 * Silence PROVE_RCU.
>  	 */
>  	rcu_read_lock();
> +	autogroup_fork(p);

Surely this doesn't need rcu.

But the real problem is that copy_process() can fail after that,
and in this case we have the unbalanced kref_get().

> +++ linux-2.6.36.git/kernel/exit.c
> @@ -174,6 +174,7 @@ repeat:
>  	write_lock_irq(&tasklist_lock);
>  	tracehook_finish_release_task(p);
>  	__exit_signal(p);
> +	sched_autogroup_exit(p);

This doesn't look right. Note that "p" can run/sleep after that
(or in parallel), set_task_rq() can use the freed ->autogroup.

Btw, I can't apply this patch...

Oleg.

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