From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>

Remove redundant mapping check.

We'd be doing exactly what putback_lru_page() is doing.  So, this code as
always unnecessary, duplicate code.  So, just let putback_lru_page()
handle this condition and conditionally unlock_page().

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/migrate.c |    8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff -puN mm/migrate.c~unevictable-lru-infrastructure-remove-redundant-page-mapping-check mm/migrate.c
--- a/mm/migrate.c~unevictable-lru-infrastructure-remove-redundant-page-mapping-check
+++ a/mm/migrate.c
@@ -728,13 +728,7 @@ unlock:
  		 * restored.
  		 */
  		list_del(&page->lru);
-		if (!page->mapping) {
-			VM_BUG_ON(page_count(page) != 1);
-			unlock_page(page);
-			put_page(page);		/* just free the old page */
-			goto end_migration;
-		} else
-			unlock = putback_lru_page(page);
+		unlock = putback_lru_page(page);
 	}
 
 	if (unlock)
_