When reading the code, I'm afraid there is a race between migrate_disable() and cpu hotplug. A scenario will like below: CPU0 CPU1 _cpu_down(); cpu_unplug_begin(); wait_for_completion() sync_unplug_thread(); complete(); race_window? /* * migrate_disable() will * not take effect since * hotplug is in progress */ __stop_machine(); I think it could happen but maybe I'm missing something. Thanks, Yong -- Only stand for myself -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html