1 files changed, 18 insertions, 8 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 0da2b2635c54..c4889abc00b6 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5060,6 +5060,17 @@ wait_to_die:
 }
 
 #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 neccessary.
  * NOTE: interrupts should be disabled by the caller
@@ -5098,7 +5109,7 @@ static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
                                        "longer affine to cpu%d\n",
                                        p->pid, p->comm, dead_cpu);
                 }
-        } while (!__migrate_task(p, dead_cpu, dest_cpu));
+        } while (!__migrate_task_irq(p, dead_cpu, dest_cpu));
 }
 
 /*
@@ -5126,7 +5137,7 @@ static void migrate_live_tasks(int src_cpu)
 {
         struct task_struct *p, *t;
 
-        write_lock_irq(&tasklist_lock);
+        read_lock(&tasklist_lock);
 
         do_each_thread(t, p) {
                 if (p == current)
@@ -5136,7 +5147,7 @@ static void migrate_live_tasks(int src_cpu)
                         move_task_off_dead_cpu(src_cpu, p);
         } while_each_thread(t, p);
 
-        write_unlock_irq(&tasklist_lock);
+        read_unlock(&tasklist_lock);
 }
 
 /*
@@ -5214,11 +5225,10 @@ static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
          * Drop lock around migration; if someone else moves it,
          * that's OK.  No task can be added to this CPU, so iteration is
          * fine.
-         * NOTE: interrupts should be left disabled  --dev@
          */
-        spin_unlock(&rq->lock);
+        spin_unlock_irq(&rq->lock);
         move_task_off_dead_cpu(dead_cpu, p);
-        spin_lock(&rq->lock);
+        spin_lock_irq(&rq->lock);
 
         put_task_struct(p);
 }
@@ -5447,14 +5457,14 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
                 kthread_stop(rq->migration_thread);
                 rq->migration_thread = NULL;
                 /* Idle task back to normal (off runqueue, low prio) */
-                rq = task_rq_lock(rq->idle, &flags);
+                spin_lock_irq(&rq->lock);
                 update_rq_clock(rq);
                 deactivate_task(rq, rq->idle, 0);
                 rq->idle->static_prio = MAX_PRIO;
                 __setscheduler(rq, rq->idle, SCHED_NORMAL, 0);
                 rq->idle->sched_class = &idle_sched_class;
                 migrate_dead_tasks(cpu);
-                task_rq_unlock(rq, &flags);
+                spin_unlock_irq(&rq->lock);
                 migrate_nr_uninterruptible(rq);
                 BUG_ON(rq->nr_running != 0);