Re: [kernel.org users] [KORG] Panics on master backend

[Oleg Nesterov]

On 08/29, Peter Zijlstra wrote:
>
> On Thu, 2011-08-25 at 15:54 +0200, Oleg Nesterov wrote:
> > > Isn't us holding ->pi_lock sufficient to stabilize task_cpu()? If its a
> > > running task the initial ->state check would have failed,
> >
> > Of course it is not TASK_RUNNING, but it can be running or not.
> >
> > > and thus its a
> > > proper wakeup when we get here and thus ->pi_lock is serializing things.
> >
> > I am not sure. If ->on_rq is true, we need rq->lock. Say, pull_task() can
> > change its cpu.
>
> If its !TASK_RUNNING but ->on_rq is true, it must be current, and
> pull_task() will never move current around.

You meant task_running() ? But it can be preempted in !TASK_RUNNING
state.

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/