Index: sys/vm/vm_map.c
===================================================================
--- sys/vm/vm_map.c
+++ sys/vm/vm_map.c
@@ -923,10 +923,12 @@
 		/* Rotate right and make y root. */	\
 		root->left = y->right;			\
 		y->right = root;			\
-		vm_map_entry_set_max_free(root);	\
+		if (root->max_free == y->max_free)	\
+			vm_map_entry_set_max_free(root);\
 		root = y;				\
 		y = root->left;				\
 	}						\
+	root->max_free = root->right ? root->right->max_free : root->next->start - root->end;\
 	/* Put root on rlist. */			\
 	root->left = rlist;				\
 	rlist = root;					\
@@ -939,10 +941,12 @@
 		/* Rotate left and make y root. */	\
 		root->right = y->left;			\
 		y->left = root;				\
-		vm_map_entry_set_max_free(root);	\
+		if (root->max_free == y->max_free)	\
+			vm_map_entry_set_max_free(root);\
 		root = y;				\
 		y = root->right;			\
 	}						\
+	root->max_free = root->left ? root->left->max_free : root->start - root->prev->end;\
 	/* Put root on llist. */			\
 	root->right = llist;				\
 	llist = root;					\
@@ -1015,18 +1019,31 @@
     vm_map_entry_t ltree, vm_map_entry_t rtree)
 {
 	vm_map_entry_t y;
+	vm_size_t max_free;
 
+	if (llist != NULL)
+		max_free = (ltree != NULL) ? ltree->max_free :
+		    llist->next->start - llist->end;
 	while (llist != NULL) {
 		y = llist->right;
 		llist->right = ltree;
-		vm_map_entry_set_max_free(llist);
+		if (llist->max_free < max_free)
+			llist->max_free = max_free;
+		else
+			max_free = llist->max_free;
 		ltree = llist;
 		llist = y;
 	}
+	if (rlist != NULL)
+		max_free = (rtree != NULL) ? rtree->max_free :
+		    rlist->start - rlist->prev->end;
 	while (rlist != NULL) {
 		y = rlist->left;
 		rlist->left = rtree;
-		vm_map_entry_set_max_free(rlist);
+		if (rlist->max_free < max_free)
+			rlist->max_free = max_free;
+		else
+			max_free = rlist->max_free;
 		rtree = rlist;
 		rlist = y;
 	}
@@ -1132,10 +1149,6 @@
 	vm_map_entry_t llist, rlist, root, y;
 
 	VM_MAP_ASSERT_LOCKED(map);
-	llist = entry->prev;
-	rlist = entry->next;
-	llist->next = rlist;
-	rlist->prev = llist;
 	root = map->root;
 	root = vm_map_splay_split(entry->start, 0, root, &llist, &rlist);
 	KASSERT(root != NULL,
@@ -1174,6 +1187,9 @@
 			root = NULL;
 		break;
 	}
+	y = entry->next;
+	y->prev = entry->prev;
+	y->prev->next = y;
 	if (root != NULL)
 		root = vm_map_splay_merge(root, llist, rlist,
 		    root->left, root->right);