On Tue, Jan 21, 2020 at 11:33:16AM -0800, John Hubbard wrote:
>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.
This is the correct one.
Before this, we don't return 1 from add_page_for_migration().
>
>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
--
Wei Yang
Help you, Help me
