[005/118] mm/migrate.c: also overwrite error when it is bigger than zero

Commit Message

Andrew Morton Jan. 31, 2020, 6:11 a.m. UTC

From: Wei Yang <[e-mail]>
Subject: mm/migrate.c: also overwrite error when it is bigger than zero

If we get here after successfully adding page to list, err would be 1 to
indicate the page is queued in the list.

Current code has two problems:

  * on success, 0 is not returned
  * on error, if add_page_for_migratioin() return 1, and the following err1
    from do_move_pages_to_node() is set, the err1 is not returned since err
    is 1

And these behaviors break the user interface.

Link: http://lkml.kernel.org/r/[e-mail]
Fixes: e0153fc2c760 ("mm: move_pages: return valid node id in status if the page is already on the target node").
Signed-off-by: Wei Yang <[e-mail]>
Acked-by: Yang Shi <[e-mail]>
Cc: John Hubbard <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Cc: Christoph Lameter <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/migrate.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

--- a/mm/migrate.c~mm-migratec-also-overwrite-error-when-it-is-bigger-than-zero
+++ a/mm/migrate.c
@@ -1676,7 +1676,7 @@  out_flush:
 	err1 = do_move_pages_to_node(mm, &pagelist, current_node);
 	if (!err1)
 		err1 = store_status(status, start, current_node, i - start);
-	if (!err)
+	if (err >= 0)
 		err = err1;
 out:
 	return err;