migrate_page_add: check for mapping == NULL

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.14-mm2/mm/mempolicy.c
===================================================================
--- linux-2.6.14-mm2.orig/mm/mempolicy.c	2005-11-12 09:07:15.000000000 -0800
+++ linux-2.6.14-mm2/mm/mempolicy.c	2005-11-12 09:07:32.000000000 -0800
@@ -217,6 +217,7 @@ static void migrate_page_add(struct vm_a
 	 * Avoid migrating a page that is shared by others and not writable.
 	 */
 	if ((flags & MPOL_MF_MOVE_ALL) ||
+	    !page->mapping ||
 	    PageAnon(page) ||
 	    mapping_writably_mapped(page->mapping) ||
 	    single_mm_mapping(vma->vm_mm, page->mapping)