1 files changed, 10 insertions, 0 deletions
diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
index 73cf6b0..9b91c1a 100644
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -336,6 +336,7 @@ vmspace_swap_count(struct vmspace *vmspace)
 	vm_map_entry_t cur;
 	int count = 0;
 
+	vm_map_lock_read(map);
 	for (cur = map->header.next; cur != &map->header; cur = cur->next) {
 		vm_object_t object;
 
@@ -351,6 +352,7 @@ vmspace_swap_count(struct vmspace *vmspace)
 			}
 		}
 	}
+	vm_map_unlock_read(map);
 	return (count);
 }
 
@@ -397,6 +399,14 @@ vm_map_unlock_read(vm_map_t map)
 	lockmgr(&(map)->lock, LK_RELEASE, NULL, curthread);
 }
 
+int
+vm_map_trylock(vm_map_t map)
+{
+
+	return (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT, NULL,
+		    curthread) == 0);
+}
+
 static __inline__ int
 _vm_map_lock_upgrade(vm_map_t map, struct thread *td) {
 	int error;