diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c
--- a/sys/kern/subr_bus.c
+++ b/sys/kern/subr_bus.c
@@ -2756,6 +2756,8 @@
 int
 device_quiesce(device_t dev)
 {
+	bus_topo_assert();
+
 	PDEBUG(("%s", DEVICENAME(dev)));
 	if (dev->busy > 0)
 		return (EBUSY);
@@ -2776,6 +2778,8 @@
 int
 device_shutdown(device_t dev)
 {
+	bus_topo_assert();
+
 	if (dev->state < DS_ATTACHED)
 		return (0);
 	return (DEVICE_SHUTDOWN(dev));
@@ -5238,7 +5242,9 @@
 		return (0);
 
 	case MOD_SHUTDOWN:
+		bus_topo_lock();
 		device_shutdown(root_bus);
+		bus_topo_unlock();
 		return (0);
 	default:
 		return (EOPNOTSUPP);