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

[Peter Zijlstra]

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.


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