Index: head/sys/net/route.c
===================================================================
--- head/sys/net/route.c
+++ head/sys/net/route.c
@@ -1733,6 +1733,8 @@
 	int family, mtu;
 	struct if_mtuinfo ifmtu;
 
+	RIB_WLOCK_ASSERT(rnh);
+
 	rt = (struct rtentry *)rnh->rnh_lookup(info->rti_info[RTAX_DST],
 	    info->rti_info[RTAX_NETMASK], &rnh->head);
 
@@ -1822,6 +1824,13 @@
 			if_updatemtu_cb(rt->rt_nodes, &ifmtu);
 		}
 	}
+
+	/*
+	 * This route change may have modified the route's gateway.  In that
+	 * case, any inpcbs that have cached this route need to invalidate their
+	 * llentry cache.
+	 */
+	rnh->rnh_gen++;
 
 	if (ret_nrt) {
 		*ret_nrt = rt;