Index: sys/vm/vm_object.c
===================================================================
--- sys/vm/vm_object.c
+++ sys/vm/vm_object.c
@@ -1054,6 +1054,8 @@
 	vm_page_iter_init(&pages, object);
 
 rescan:
+	KASSERT(pctrie_iter_is_reset(&pages),
+	    ("%s: pctrie_iter not reset for retry", __func__));
 	curgeneration = object->generation;
 
 	for (p = vm_radix_iter_lookup_ge(&pages, tstart); p != NULL; p = np) {
@@ -1342,6 +1344,8 @@
 
 	vm_page_iter_init(&pages, object);
 relookup:
+	KASSERT(pctrie_iter_is_reset(&pages),
+	    ("%s: pctrie_iter not reset for retry", __func__));
 	VM_OBJECT_WLOCK(object);
 	if (!vm_object_advice_applies(object, advice)) {
 		VM_OBJECT_WUNLOCK(object);