Index: vm/vm_map.c
===================================================================
--- vm/vm_map.c	(revision 251557)
+++ vm/vm_map.c	(working copy)
@@ -2204,9 +2204,10 @@
  *
  *	Implements both kernel and user unwiring.
  */
+
 int
-vm_map_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
-    int flags)
+vm_map_unwire_count(vm_map_t map, vm_offset_t start, vm_offset_t end,
+    int flags, vm_offset_t *count)
 {
 	vm_map_entry_t entry, first_entry, tmp_entry;
 	vm_offset_t saved_start;
@@ -2214,6 +2215,7 @@
 	int rv;
 	boolean_t need_wakeup, result, user_unwire;
 
+	*count = 0;
 	user_unwire = (flags & VM_MAP_WIRE_USER) ? TRUE : FALSE;
 	vm_map_lock(map);
 	VM_MAP_RANGE_CHECK(map, start, end);
@@ -2328,6 +2330,7 @@
 				    entry->object.vm_object != NULL &&
 				    (entry->object.vm_object->flags &
 				    OBJ_FICTITIOUS) != 0);
+				*count += entry->end - entry->start;
 			}
 		}
 		KASSERT(entry->eflags & MAP_ENTRY_IN_TRANSITION,
@@ -2346,6 +2349,16 @@
 	return (rv);
 }
 
+int
+vm_map_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
+    int flags)
+{
+	vm_offset_t count;
+
+	return vm_map_unwire_count(map, start, end, flags, &count);
+}
+
+
 /*
  *	vm_map_wire:
  *
Index: vm/vm_map.h
===================================================================
--- vm/vm_map.h	(revision 251557)
+++ vm/vm_map.h	(working copy)
@@ -388,6 +388,8 @@
 void vm_init2 (void);
 int vm_map_stack (vm_map_t, vm_offset_t, vm_size_t, vm_prot_t, vm_prot_t, int);
 int vm_map_growstack (struct proc *p, vm_offset_t addr);
+int vm_map_unwire_count(vm_map_t map, vm_offset_t start, vm_offset_t end,
+    int flags, vm_offset_t *count);
 int vm_map_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
     int flags);
 int vm_map_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
Index: vm/vm_mmap.c
===================================================================
--- vm/vm_mmap.c	(revision 251557)
+++ vm/vm_mmap.c	(working copy)
@@ -1222,7 +1222,7 @@
 	struct thread *td;
 	struct munlock_args *uap;
 {
-	vm_offset_t addr, end, last, start;
+	vm_offset_t addr, end, last, start, unwired;
 	vm_size_t size;
 	int error;
 
@@ -1236,12 +1236,12 @@
 	end = round_page(last);
 	if (last < addr || end < addr)
 		return (EINVAL);
-	error = vm_map_unwire(&td->td_proc->p_vmspace->vm_map, start, end,
-	    VM_MAP_WIRE_USER | VM_MAP_WIRE_NOHOLES);
+	error = vm_map_unwire_count(&td->td_proc->p_vmspace->vm_map, start, end,
+	    VM_MAP_WIRE_USER | VM_MAP_WIRE_NOHOLES, &unwired);
 #ifdef RACCT
 	if (error == KERN_SUCCESS) {
 		PROC_LOCK(td->td_proc);
-		racct_sub(td->td_proc, RACCT_MEMLOCK, ptoa(end - start));
+		racct_sub(td->td_proc, RACCT_MEMLOCK, unwired);
 		PROC_UNLOCK(td->td_proc);
 	}
 #endif