Re: [PATCH 1/1] ptrace: do_wait(traced_leader_killed_by_mt_exec) canblock forever

From: Tejun Heo
Date: Fri Jul 22 2011 - 04:44:39 EST


On Thu, Jul 21, 2011 at 08:00:43PM +0200, Oleg Nesterov wrote:
> It is racy, exit_notify() does __wake_up_parent() too. But in the
> likely case it triggers the problem: de_thread() does release_task()
> and the old leader goes away without the notification, the tracer
> sleeps in do_wait() without children/tracees.
> Change de_thread() to do __wake_up_parent(traced_leader->parent).
> Since it is already EXIT_DEAD we can do this without ptrace_unlink(),
> EXIT_DEAD threads do not exist from do_wait's pov.
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>

Nice catch as always. :)

Acked-by: Tejun Heo <tj@xxxxxxxxxx>


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