[PATCH 1/5] mm: stop returning -ENOENT from sys_move_pages() if nothing got migrated

[Brice Goglin <Brice.Goglin@inria.fr>]

There is no point in returning -ENOENT from sys_move_pages() if all
pages were already on the right node, while we return 0 if only 1 page
was not. Most application don't know where their pages are allocated,
so it's not an error to try to migrate them anyway.

Just return 0 and let the status array in user-space be checked if the
application needs details.

It will make the upcoming chunked-move_pages() support much easier.

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
---
 mm/migrate.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 2a80136..e505b2f 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -926,11 +926,10 @@ set_status:
 		pp->status = err;
 	}
 
+	err = 0;
 	if (!list_empty(&pagelist))
 		err = migrate_pages(&pagelist, new_page_node,
 				(unsigned long)pm);
-	else
-		err = -ENOENT;
 
 	up_read(&mm->mmap_sem);
 	return err;
-- 
1.5.6.5