Index: sys/vm/vm_page.c
===================================================================
--- sys/vm/vm_page.c
+++ sys/vm/vm_page.c
@@ -1484,7 +1484,7 @@
  */
 static __always_inline int
 vm_page_insert_lookup(vm_page_t m, vm_object_t object, vm_pindex_t pindex,
-    vm_page_t mpred, bool lookup)
+    vm_page_t mpred, bool lookup, struct pctrie_iter *pages, bool hasIter)
 {
 	int error;
 
@@ -1505,6 +1505,8 @@
 	 */
 	if (lookup)
 		error = vm_radix_insert_lookup_lt(&object->rtree, m, &mpred);
+	else if (hasIter)
+		error = vm_radix_iter_insert(pages, m);
 	else
 		error = vm_radix_insert(&object->rtree, m);
 	if (__predict_false(error != 0)) {
@@ -1522,6 +1524,17 @@
 	return (0);
 }
 
+/*
+ * Try to insert the given page at the given pindex, using an iterator.
+ */
+static int
+vm_page_iter_insert(struct pctrie_iter *pages, vm_page_t m, vm_object_t object,
+    vm_pindex_t pindex, vm_page_t mpred)
+{
+	return (vm_page_insert_lookup(m, object, pindex,
+	    mpred, false, pages, true));
+}
+
 /*
  *	vm_page_insert:		[ internal use only ]
  *
@@ -1532,7 +1545,8 @@
 int
 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex)
 {
-	return (vm_page_insert_lookup(m, object, pindex, NULL, true));
+	return (vm_page_insert_lookup(m, object, pindex, NULL, true,
+	    NULL, false));
 }
 
 /*
@@ -1549,7 +1563,8 @@
 vm_page_insert_after(vm_page_t m, vm_object_t object, vm_pindex_t pindex,
     vm_page_t mpred)
 {
-	return (vm_page_insert_lookup(m, object, pindex, mpred, false));
+	return (vm_page_insert_lookup(m, object, pindex, mpred, false,
+	    NULL, false));
 }
 
 /*
@@ -2372,6 +2387,7 @@
     int req, u_long npages, vm_paddr_t low, vm_paddr_t high, u_long alignment,
     vm_paddr_t boundary, vm_memattr_t memattr)
 {
+	struct pctrie_iter pages;
 	vm_page_t m, m_ret, mpred;
 	u_int busy_lock, flags, oflags;
 
@@ -2390,7 +2406,8 @@
 	    object));
 	KASSERT(npages > 0, ("vm_page_alloc_contig: npages is zero"));
 
-	mpred = vm_radix_lookup_le(&object->rtree, pindex);
+	vm_page_iter_init(&pages, object);
+	mpred = vm_radix_iter_lookup_le(&pages, pindex);
 	KASSERT(mpred == NULL || mpred->pindex != pindex,
 	    ("vm_page_alloc_contig: pindex already allocated"));
 	for (;;) {
@@ -2439,7 +2456,7 @@
 			m->ref_count = 1;
 		m->a.act_count = 0;
 		m->oflags = oflags;
-		if (vm_page_insert_after(m, object, pindex, mpred)) {
+		if (vm_page_iter_insert(&pages, m, object, pindex, mpred)) {
 			if ((req & VM_ALLOC_WIRED) != 0)
 				vm_wire_sub(npages);
 			KASSERT(m->object == NULL,
Index: sys/vm/vm_radix.h
===================================================================
--- sys/vm/vm_radix.h
+++ sys/vm/vm_radix.h
@@ -257,6 +257,19 @@
 	return (VM_RADIX_PCTRIE_ITER_STEP_GE(pages));
 }
 
+/*
+ * Initialize an iterator pointing to the page with the greatest pindex that is
+ * less than or equal to the specified pindex, or NULL if there are no such
+ * pages.  Return the page.
+ *
+ * Requires that access be externally synchronized by a lock.
+ */
+static __inline vm_page_t
+vm_radix_iter_lookup_le(struct pctrie_iter *pages, vm_pindex_t index)
+{
+	return (VM_RADIX_PCTRIE_ITER_LOOKUP_LE(pages, index));
+}
+
 /*
  * Update the iterator to point to the page with the pindex that is one greater
  * than the current pindex, or NULL if there is no such page.  Return the page.