Index: linux-2.6.17-rc2-mm1/mm/migrate.c
===================================================================
--- linux-2.6.17-rc2-mm1.orig/mm/migrate.c	2006-04-27 23:39:11.853319378 -0700
+++ linux-2.6.17-rc2-mm1/mm/migrate.c	2006-04-28 06:56:36.856624280 -0700
@@ -248,6 +248,11 @@
 
 /*
  * Remove or replace the page in the mapping
+ *
+ * The number of remaining references must be:
+ * 1 for anonymous pages without a mapping
+ * 2 for pages with a mapping
+ * 3 for pages with a mapping and PagePrivate set.
  */
 static int migrate_page_move_mapping(struct address_space *mapping,
 		struct page *newpage, struct page *page)