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
@@ -267,6 +267,7 @@
 
 	sbuf_new_for_sysctl(&sb, NULL, 1024, req);
 	sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
+	bus_topo_lock();
 	switch (arg2) {
 	case DEVICE_SYSCTL_DESC:
 		sbuf_cat(&sb, dev->desc ? dev->desc : "");
@@ -284,10 +285,12 @@
 		sbuf_cat(&sb, dev->parent ? dev->parent->nameunit : "");
 		break;
 	default:
-		sbuf_delete(&sb);
-		return (EINVAL);
+		error = EINVAL;
+		goto out;
 	}
 	error = sbuf_finish(&sb);
+out:
+	bus_topo_unlock();
 	sbuf_delete(&sb);
 	return (error);
 }
@@ -307,33 +310,33 @@
 	    dev->nameunit + strlen(dc->name),
 	    CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, "", "device_index");
 	SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
-	    OID_AUTO, "%desc", CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT,
+	    OID_AUTO, "%desc", CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
 	    dev, DEVICE_SYSCTL_DESC, device_sysctl_handler, "A",
 	    "device description");
 	SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
 	    OID_AUTO, "%driver",
-	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT,
+	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
 	    dev, DEVICE_SYSCTL_DRIVER, device_sysctl_handler, "A",
 	    "device driver name");
 	SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
 	    OID_AUTO, "%location",
-	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT,
+	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
 	    dev, DEVICE_SYSCTL_LOCATION, device_sysctl_handler, "A",
 	    "device location relative to parent");
 	SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
 	    OID_AUTO, "%pnpinfo",
-	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT,
+	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
 	    dev, DEVICE_SYSCTL_PNPINFO, device_sysctl_handler, "A",
 	    "device identification");
 	SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
 	    OID_AUTO, "%parent",
-	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT,
+	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
 	    dev, DEVICE_SYSCTL_PARENT, device_sysctl_handler, "A",
 	    "parent device");
 	if (bus_get_domain(dev, &domain) == 0)
 		SYSCTL_ADD_INT(&dev->sysctl_ctx,
 		    SYSCTL_CHILDREN(dev->sysctl_tree), OID_AUTO, "%domain",
-		    CTLFLAG_RD, NULL, domain, "NUMA domain");
+		    CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, domain, "NUMA domain");
 }
 
 static void