--- mm/filemap.c

+++ mm/filemap.c

@@ -1030,6 +1030,9 @@ find_page:

goto page_not_up_to_date;

if (!trylock_page(page))

goto page_not_up_to_date;

+ /* Did it get truncated before we got the lock? */

+ if (!page->mapping)

+ goto page_not_up_to_date_locked;

if (!mapping->a_ops->is_partially_uptodate(page,

desc, offset))

goto page_not_up_to_date_locked;