Re: [Patch v2] mm/migrate.c: also overwrite error when it is bigger than zero
From: John Hubbard
Date: Tue Jan 21 2020 - 14:33:19 EST
On 1/20/20 6:34 PM, Wei Yang wrote:
On Tue, Jan 21, 2020 at 09:53:26AM +0800, Wei Yang wrote:
On Sun, Jan 19, 2020 at 02:57:53PM +0800, Wei Yang wrote:
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.
Fixes: e0153fc2c760 ("mm: move_pages: return valid node id in status if the
page is already on the target node").
The Fixes tag should be different, right? Because I don't think that
commit introduced this problem.
thanks,
--
John Hubbard
NVIDIA
Signed-off-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
---
v2:
* put more words to explain the error case
---
mm/migrate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 86873b6f38a7..430fdccc733e 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1676,7 +1676,7 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
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;
Ok, as mentioned by Yang and Michal, only err == 0 means no error.
Sounds this regression should be fixed in another place. Let me send out
another patch.
Hmm... I took another look into the case, this fix should work.
But yes, the semantic here is a little confusion. Look forward your comments
here.
out:
return err;
--
2.17.1
--
Wei Yang
Help you, Help me
thanks,
--
John Hubbard
NVIDIA