- Remove vm_object_init2(). It is unused.

- Add a mtx_destroy() to vm_object_collapse().  (This allows a bzero()
   to migrate from _vm_object_allocate() to vm_object_zinit(), where it
   will be performed less often.)

sys/vm/vm_map.c

@@ -275,7 +275,6 @@ vm_init2(void)
 #endif
 	    vmspace_zinit, vmspace_zfini, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
 	pmap_init2();
-	vm_object_init2();
 }
 
 static __inline void

sys/vm/vm_object.c

@@ -180,6 +180,7 @@ vm_object_zinit(void *mem, int size)
 	vm_object_t object;
 
 	object = (vm_object_t)mem;
+	bzero(&object->mtx, sizeof(object->mtx));
 
 	/* These are true for any object that has been freed */
 	object->paging_in_progress = 0;
@@ -192,7 +193,6 @@ _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object)
 {
 	int incr;
 
-	bzero(&object->mtx, sizeof(object->mtx));
 	mtx_init(&object->mtx, "vm object", NULL, MTX_DEF);
 
 	TAILQ_INIT(&object->memq);
@@ -252,11 +252,6 @@ vm_object_init(void)
 	uma_prealloc(obj_zone, VM_OBJECTS_INIT);
 }
 
-void
-vm_object_init2(void)
-{
-}
-
 void
 vm_object_set_flag(vm_object_t object, u_short bits)
 {
@@ -1630,6 +1625,8 @@ vm_object_collapse(vm_object_t object)
 			);
 			mtx_unlock(&vm_object_list_mtx);
 
+			mtx_destroy(&backing_object->mtx);
+
 			uma_zfree(obj_zone, backing_object);
 
 			object_collapses++;

sys/vm/vm_object.h

@@ -207,7 +207,6 @@ void vm_object_reference (vm_object_t);
 void vm_object_shadow (vm_object_t *, vm_ooffset_t *, vm_size_t);
 void vm_object_split(vm_map_entry_t);
 void vm_object_madvise (vm_object_t, vm_pindex_t, int, int);
-void vm_object_init2 (void);
 #endif				/* _KERNEL */
 
 #endif				/* _VM_OBJECT_ */