migration: fix writepage error

Page migration's writeout() has got understandably confused by the nasty
AOP_WRITEPAGE_ACTIVATE case: as in normal success, a writepage() error has
unlocked the page, so writeout() then needs to relock it.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 4 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 385db89f0c33..1e0d6b237f44 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -522,15 +522,12 @@ static int writeout(struct address_space *mapping, struct page *page)
         remove_migration_ptes(page, page);
 
         rc = mapping->a_ops->writepage(page, &wbc);
-        if (rc < 0)
-                /* I/O Error writing */
-                return -EIO;
 
         if (rc != AOP_WRITEPAGE_ACTIVATE)
                 /* unlocked. Relock */
                 lock_page(page);
 
-        return -EAGAIN;
+        return (rc < 0) ? -EIO : -EAGAIN;
 }
 
 /*