Perform vm_object_lock() and vm_object_unlock() around

vm_object_page_remove().

sys/kern/vfs_subr.c

@@ -1171,8 +1171,10 @@ vinvalbuf(vp, flags, cred, td, slpflag, slptimeo)
 	 * Destroy the copy in the VM cache, too.
 	 */
 	if (VOP_GETVOBJECT(vp, &object) == 0) {
+		vm_object_lock(object);
 		vm_object_page_remove(object, 0, 0,
 			(flags & V_SAVE) ? TRUE : FALSE);
+		vm_object_unlock(object);
 	}
 
 #ifdef INVARIANTS

sys/vm/vnode_pager.c

@@ -311,8 +311,10 @@ vnode_pager_setsize(vp, nsize)
 		vm_freeze_copyopts(object, OFF_TO_IDX(nsize), object->size);
 #endif
 		if (nobjsize < object->size) {
+			vm_object_lock(object);
 			vm_object_page_remove(object, nobjsize, object->size,
 				FALSE);
+			vm_object_unlock(object);
 		}
 		/*
 		 * this gets rid of garbage at the end of a page that is now