sched: fix sched_fork()

fix sched_fork(): large latencies at new task creation time because
the ->vruntime was not fixed up cross-CPU, if the parent got migrated
after the child's CPU got set up.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

kernel/sched.c

@@ -1657,7 +1657,7 @@ void sched_fork(struct task_struct *p, int clone_flags)
 #ifdef CONFIG_SMP
 	cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
 #endif
-	__set_task_cpu(p, cpu);
+	set_task_cpu(p, cpu);
 
 	/*
 	 * Make sure we do not leak PI boosting priority to the child: