Index: vm_map.c
===================================================================
--- vm_map.c
+++ vm_map.c
@@ -2192,7 +2192,18 @@
 	 * entry BEFORE this one, so that this entry has the specified
 	 * starting address.
 	 */
-	vm_map_simplify_entry(map, entry);
+	if ((entry->eflags & MAP_ENTRY_NOMERGE_MASK) == 0 &&
+	    (vm_map_mergeable_neighbors(entry->prev, entry) ||
+	     vm_map_mergeable_neighbors(entry, entry->next))) {
+		printf("%s: simplifying entry start %jx end %jx next_read %jx "
+		    "max_free %jx eflags %jx object-type %d\n", __func__,
+		    (uintmax_t)entry->start, (uintmax_t)entry->end,
+		    (uintmax_t)entry->next_read, (uintmax_t)entry->max_free,
+		    (uintmax_t)entry->eflags,
+		    entry->object.vm_object ? entry->object.vm_object->type : -1);
+		vm_map_simplify_entry(map, entry);
+	}
+
 	vm_map_entry_charge_object(map, entry);
 	new_entry = vm_map_entry_create(map);
 	*new_entry = *entry;