diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -1599,14 +1599,19 @@
 		/*
 		 * The page was left invalid.  Likely placed there by
 		 * an incomplete fault.  Just remove and ignore.
+		 *
+		 * However, if the map entry is wired, we must hang on to the
+		 * page to avoid leaking it, since the entry owns the wiring(s).
+		 * Invalid, wired pages can arise here if the backing pager is
+		 * truncated.
 		 */
-		if (vm_page_none_valid(m)) {
+		if (vm_page_none_valid(m) && entry->wired_count == 0) {
 			if (vm_page_iter_remove(&pages, m))
 				vm_page_free(m);
 			continue;
 		}
 
-		/* vm_page_iter_rename() will dirty the page. */
+		/* vm_page_iter_rename() will dirty the page if it is valid. */
 		if (!vm_page_iter_rename(&pages, m, new_object, m->pindex -
 		    offidxstart)) {
 			vm_page_xunbusy(m);
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -2044,9 +2044,9 @@
  *	      moving the page from object A to B, and will then later move
  *	      the backing store from A to B and we can't have a conflict.
  *
- *	Note: we *always* dirty the page.  It is necessary both for the
- *	      fact that we moved it, and because we may be invalidating
- *	      swap.
+ *	Note: callers will generally pass a valid page, in which case will we
+ *	      dirty it.  This is necessary both for the fact that we moved it,
+ *	      and because we may be invalidating swap.
  *
  *	The objects must be locked.
  */
@@ -2087,7 +2087,8 @@
 	m->object = new_object;
 
 	vm_page_insert_radixdone(m, new_object, mpred);
-	vm_page_dirty(m);
+	if (vm_page_any_valid(m))
+		vm_page_dirty(m);
 	vm_pager_page_inserted(new_object, m);
 	return (true);
 }