worker_thread: don't play with SIGCHLD and numa policy

worker_thread() inherits ignored SIGCHLD and numa_default_policy() from its
parent, kthreadd.  No need to setup this again.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/workqueue.c

@@ -289,23 +289,11 @@ static int worker_thread(void *__cwq)
 {
 	struct cpu_workqueue_struct *cwq = __cwq;
 	DEFINE_WAIT(wait);
-	struct k_sigaction sa;
 
 	if (!cwq->wq->freezeable)
 		current->flags |= PF_NOFREEZE;
 
 	set_user_nice(current, -5);
-	/*
-	 * We inherited MPOL_INTERLEAVE from the booting kernel.
-	 * Set MPOL_DEFAULT to insure node local allocations.
-	 */
-	numa_default_policy();
-
-	/* SIG_IGN makes children autoreap: see do_notify_parent(). */
-	sa.sa.sa_handler = SIG_IGN;
-	sa.sa.sa_flags = 0;
-	siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
-	do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0);
 
 	for (;;) {
 		prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);