Re: [patch] sched: prevent bound kthreads from changing cpus_allowed

[Oleg Nesterov]

On 06/05, David Rientjes wrote:
>
> Kthreads that have called kthread_bind() are bound to specific cpus, so
> other tasks should not be able to change their cpus_allowed from under
> them.  Otherwise, it is possible to move kthreads, such as the migration
> or software watchdog threads, so they are not allowed access to the cpu
> they work on.

Imho, this is very good change, but...

> @@ -180,6 +180,7 @@ void kthread_bind(struct task_struct *k, unsigned int cpu)
>  	set_task_cpu(k, cpu);
>  	k->cpus_allowed = cpumask_of_cpu(cpu);
>  	k->rt.nr_cpus_allowed = 1;
> +	k->flags |= PF_THREAD_BOUND;

What if user-space moves this task right before "|= PF_THREAD_BOUND" ?

Oleg.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/