/* Must be high prio: stop_machine expects to yield to it. */
                rq = task_rq_lock(p, &flags);
                __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1);
-
-               /* Update our root-domain */
-               if (rq->rd) {
-                       BUG_ON(!cpu_isset(cpu, rq->rd->span));
-                       cpu_set(cpu, rq->rd->online);
-               }
-
                task_rq_unlock(rq, &flags);
                cpu_rq(cpu)->migration_thread = p;
                break;
        case CPU_ONLINE_FROZEN:
                /* Strictly unnecessary, as first user will wake it. */
                wake_up_process(cpu_rq(cpu)->migration_thread);
+
+               /* Update our root-domain */
+               rq = cpu_rq(cpu);
+               spin_lock_irqsave(&rq->lock, flags);
+               if (rq->rd) {
+                       BUG_ON(!cpu_isset(cpu, rq->rd->span));
+                       cpu_set(cpu, rq->rd->online);
+               }
+               spin_unlock_irqrestore(&rq->lock, flags);
                break;
 
 #ifdef CONFIG_HOTPLUG_CPU
        rq->rd = rd;
 
        cpu_set(rq->cpu, rd->span);
+       if (cpu_isset(rq->cpu, cpu_online_map))
+               cpu_set(rq->cpu, rd->online);
 
        for (class = sched_class_highest; class; class = class->next) {
                if (class->join_domain)