Index: linux-2.6/lib/radix-tree.c
===================================================================
--- linux-2.6.orig/lib/radix-tree.c	2006-01-03 19:05:57.000000000 +1100
+++ linux-2.6/lib/radix-tree.c	2006-01-17 15:17:36.000000000 +1100
@@ -233,6 +233,8 @@ int radix_tree_insert(struct radix_tree_
 	int offset;
 	int error;
 
+	BUG_ON((unsigned long)item < PAGE_OFFSET);
+
 	/* Make sure the tree is high enough.  */
 	if ((!index && !root->rnode) ||
 			index > radix_tree_maxindex(root->height)) {
@@ -334,6 +336,8 @@ void *radix_tree_lookup(struct radix_tre
 	void **slot;
 
 	slot = __lookup_slot(root, index);
+	if (slot && *slot)
+		BUG_ON((unsigned long)(*slot) < PAGE_OFFSET);
 	return slot != NULL ? *slot : NULL;
 }
 EXPORT_SYMBOL(radix_tree_lookup);