exit: Stop poorly open coding do_task_dead in make_task_dead

When the kernel detects it is oops or otherwise force killing a task
while it exits the code poorly attempts to permanently stop the task
from scheduling.

I say poorly because it is possible for a task in TASK_UINTERRUPTIBLE
to be woken up.

As it makes no sense for the task to continue call do_task_dead
instead which actually does the work and permanently removes the task
from the scheduler.  Guaranteeing the task will never be woken
up again.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

kernel/exit.c

@@ -886,8 +886,7 @@ void __noreturn make_task_dead(int signr)
 	if (unlikely(tsk->flags & PF_EXITING)) {
 		pr_alert("Fixing recursive fault but reboot is needed!\n");
 		futex_exit_recursive(tsk);
-		set_current_state(TASK_UNINTERRUPTIBLE);
-		schedule();
+		do_task_dead();
 	}
 
 	do_exit(signr);