revert "sched: Fix fork() error path to not crash"

To make way for "fork: fix error handling in dup_task()", which fixes the
errors more completely.

Cc: Salman Qazi <sqazi@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/fork.c

@@ -304,17 +304,12 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 	}
 
 	err = arch_dup_task_struct(tsk, orig);
-
-	/*
-	 * We defer looking at err, because we will need this setup
-	 * for the clean up path to work correctly.
-	 */
-	tsk->stack = ti;
-	setup_thread_stack(tsk, orig);
-
 	if (err)
 		goto out;
 
+	tsk->stack = ti;
+
+	setup_thread_stack(tsk, orig);
 	clear_user_return_notifier(tsk);
 	clear_tsk_need_resched(tsk);
 	stackend = end_of_stack(tsk);