Index: sys/vm/vm_page.c
===================================================================
--- sys/vm/vm_page.c	(revision 232652)
+++ sys/vm/vm_page.c	(working copy)
@@ -766,6 +766,63 @@
 }
 
 /*
+ *	vm_page_splay:
+ *
+ *	Implements Sleator and Tarjan's top-down splay algorithm.  Returns
+ *	the vm_page containing the given pindex.  If, however, that
+ *	pindex is not found in the vm_object, returns a vm_page that is
+ *	adjacent to the pindex, coming before or after it.
+ */
+vm_page_t
+vm_page_splay(vm_pindex_t pindex, vm_page_t root)
+{
+	struct vm_page dummy;
+	vm_page_t lefttreemax, righttreemin, y;
+
+	if (root == NULL)
+		return (root);
+	lefttreemax = righttreemin = &dummy;
+	for (;; root = y) {
+		if (pindex < root->pindex) {
+			if ((y = root->left) == NULL)
+				break;
+			if (pindex < y->pindex) {
+				/* Rotate right. */
+				root->left = y->right;
+				y->right = root;
+				root = y;
+				if ((y = root->left) == NULL)
+					break;
+			}
+			/* Link into the new root's right tree. */
+			righttreemin->left = root;
+			righttreemin = root;
+		} else if (pindex > root->pindex) {
+			if ((y = root->right) == NULL)
+				break;
+			if (pindex > y->pindex) {
+				/* Rotate left. */
+				root->right = y->left;
+				y->left = root;
+				root = y;
+				if ((y = root->right) == NULL)
+					break;
+			}
+			/* Link into the new root's left tree. */
+			lefttreemax->right = root;
+			lefttreemax = root;
+		} else
+			break;
+	}
+	/* Assemble the new root. */
+	lefttreemax->right = root->left;
+	righttreemin->left = root->right;
+	root->left = dummy.right;
+	root->right = dummy.left;
+	return (root);
+}
+
+/*
  *	vm_page_insert:		[ internal use only ]
  *
  *	Inserts the given mem entry into the object and object list.
Index: sys/vm/vm_page.h
===================================================================
--- sys/vm/vm_page.h	(revision 232652)
+++ sys/vm/vm_page.h	(working copy)
@@ -130,6 +130,8 @@
 struct vm_page {
 	TAILQ_ENTRY(vm_page) pageq;	/* queue info for FIFO queue or free list (Q) */
 	TAILQ_ENTRY(vm_page) listq;	/* pages in same object (O) 	*/
+	struct vm_page *left;		/* splay tree link (O)		*/
+	struct vm_page *right;		/* splay tree link (O)		*/
 
 	vm_object_t object;		/* which object am I in (O,P)*/
 	vm_pindex_t pindex;		/* offset into object (O,P) */
@@ -398,6 +400,7 @@
 void vm_page_requeue(vm_page_t m);
 void vm_page_set_valid_range(vm_page_t m, int base, int size);
 void vm_page_sleep(vm_page_t m, const char *msg);
+vm_page_t vm_page_splay(vm_pindex_t, vm_page_t);
 vm_offset_t vm_page_startup(vm_offset_t vaddr);
 void vm_page_unhold_pages(vm_page_t *ma, int count);
 void vm_page_unwire (vm_page_t, int);