From bcc2cf1d80b2edf0df804ea5c4b063d93340b3f5 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Mon, 15 Mar 2010 10:10:10 +0100
Subject: [PATCH] --- yaml --- r: 191400 b: refs/heads/master c:
 1445c08d06c5594895b4fae952ef8a457e89c390 h: refs/heads/master v: v3

---
 [refs]               |  2 +-
 trunk/kernel/sched.c | 30 +++++++++++++++---------------
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/[refs] b/[refs]
index 8362b737812c..6436292aa078 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 897f0b3c3ff40b443c84e271bef19bd6ae885195
+refs/heads/master: 1445c08d06c5594895b4fae952ef8a457e89c390
diff --git a/trunk/kernel/sched.c b/trunk/kernel/sched.c
index c0b3ebc16317..27774b5aeb61 100644
--- a/trunk/kernel/sched.c
+++ b/trunk/kernel/sched.c
@@ -5448,29 +5448,29 @@ static int migration_thread(void *data)
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
-
-static int __migrate_task_irq(struct task_struct *p, int src_cpu, int dest_cpu)
-{
-	int ret;
-
-	local_irq_disable();
-	ret = __migrate_task(p, src_cpu, dest_cpu);
-	local_irq_enable();
-	return ret;
-}
-
 /*
  * Figure out where task on dead CPU should go, use force if necessary.
  */
 static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
 {
-	int dest_cpu;
-
+	struct rq *rq = cpu_rq(dead_cpu);
+	int needs_cpu, uninitialized_var(dest_cpu);
+	unsigned long flags;
 again:
-	dest_cpu = select_fallback_rq(dead_cpu, p);
+	local_irq_save(flags);
+
+	raw_spin_lock(&rq->lock);
+	needs_cpu = (task_cpu(p) == dead_cpu) && (p->state != TASK_WAKING);
+	if (needs_cpu)
+		dest_cpu = select_fallback_rq(dead_cpu, p);
+	raw_spin_unlock(&rq->lock);
 
 	/* It can have affinity changed while we were choosing. */
-	if (unlikely(!__migrate_task_irq(p, dead_cpu, dest_cpu)))
+	if (needs_cpu)
+		needs_cpu = !__migrate_task(p, dead_cpu, dest_cpu);
+	local_irq_restore(flags);
+
+	if (unlikely(needs_cpu))
 		goto again;
 }