rmap: remove obsolete check from __page_check_anon_rmap()

When an anonymous page is inherited from a parent process, the
vma->anon_vma can differ from the page anon_vma.  This can trip up
__page_check_anon_rmap, which is indirectly called from do_swap_page().

Remove that obsolete check to prevent an oops.

Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/rmap.c b/mm/rmap.c
index be34094..23ecd0a 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -754,9 +754,6 @@ static void __page_check_anon_rmap(struct page *page,
         * are initially only visible via the pagetables, and the pte is locked
         * over the call to page_add_new_anon_rmap.
         */
-       struct anon_vma *anon_vma = vma->anon_vma;
-       anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
-       BUG_ON(page->mapping != (struct address_space *)anon_vma);
        BUG_ON(page->index != linear_page_index(vma, address));
 #endif
 }