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
@@ -1996,10 +1996,8 @@
 }
 
 /*
- * Allocate a page in the specified object with the given page index.  To
- * optimize insertion of the page into the object, the caller must also specify
- * the resident page in the object with largest index smaller than the given
- * page index, or NULL if no such page exists.
+ * Allocate a page in the specified object with the given page index.  If the
+ * object lock is dropped and regained, the pages iter is reset.
  */
 vm_page_t
 vm_page_alloc_iter(vm_object_t object, vm_pindex_t pindex, int req,
@@ -5189,6 +5187,7 @@
 				break;
 			m = vm_page_alloc_iter(object, pindex + i,
 			    pflags | VM_ALLOC_COUNT(count - i), &pages);
+			/* pages was reset if alloc_iter lost the lock. */
 			if (m == NULL) {
 				if ((allocflags & (VM_ALLOC_NOWAIT |
 				    VM_ALLOC_WAITFAIL)) != 0)