sched/numa: Kill the wrong/dead TASK_DEAD check in task_numa_fault()

current->state == TASK_DEAD means that the task is doing its
last schedule(), page fault is obviously impossible at this
stage.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140921194743.GA30114@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

@@ -1817,10 +1817,6 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
 	if (!p->mm)
 		return;
 
-	/* Do not worry about placement if exiting */
-	if (p->state == TASK_DEAD)
-		return;
-
 	/* Allocate buffer to track faults on a per-node basis */
 	if (unlikely(!p->numa_faults_memory)) {
 		int size = sizeof(*p->numa_faults_memory) *