Index: head/sys/vm/vm_map.c
===================================================================
--- head/sys/vm/vm_map.c
+++ head/sys/vm/vm_map.c
@@ -1487,8 +1487,23 @@
 static int cluster_anon = 1;
 SYSCTL_INT(_vm, OID_AUTO, cluster_anon, CTLFLAG_RW,
     &cluster_anon, 0,
-    "Cluster anonymous mappings");
+    "Cluster anonymous mappings: 0 = no, 1 = yes if no hint, 2 = always");
 
+static bool
+clustering_anon_allowed(vm_offset_t addr)
+{
+
+	switch (cluster_anon) {
+	case 0:
+		return (false);
+	case 1:
+		return (addr == 0);
+	case 2:
+	default:
+		return (true);
+	}
+}
+
 static long aslr_restarts;
 SYSCTL_LONG(_vm, OID_AUTO, aslr_restarts, CTLFLAG_RD,
     &aslr_restarts, 0,
@@ -1593,7 +1608,7 @@
 	} else
 		alignment = 0;
 	en_aslr = (map->flags & MAP_ASLR) != 0;
-	update_anon = cluster = cluster_anon != 0 &&
+	update_anon = cluster = clustering_anon_allowed(*addr) &&
 	    (map->flags & MAP_IS_SUB_MAP) == 0 && max_addr == 0 &&
 	    find_space != VMFS_NO_SPACE && object == NULL &&
 	    (cow & (MAP_INHERIT_SHARE | MAP_STACK_GROWS_UP |