Index: linux-2.6.17-rc5-mm2/mm/swapfile.c
===================================================================
--- linux-2.6.17-rc5-mm2.orig/mm/swapfile.c	2006-06-01 10:03:07.127259731 -0700
+++ linux-2.6.17-rc5-mm2/mm/swapfile.c	2006-06-05 13:40:45.887291175 -0700
@@ -1408,8 +1408,13 @@ asmlinkage long sys_swapon(const char __
 		spin_unlock(&swap_lock);
 		goto out;
 	}
-	if (type >= nr_swapfiles)
+	if (type >= nr_swapfiles) {
+		if (nr_swapfiles >= MAX_SWAPFILES) {
+			spin_unlock(&swap_lock);
+			goto out;
+		}
 		nr_swapfiles = type+1;
+	}
 	INIT_LIST_HEAD(&p->extent_list);
 	p->flags = SWP_USED;
 	p->swap_file = NULL;