On 2022/4/11 22:10, Christoph Hellwig wrote:
> On Sat, Apr 09, 2022 at 03:38:45PM +0800, Miaohe Lin wrote:
>> We might fail to isolate huge page due to e.g. the page is under migration
>> which cleared HPageMigratable. So we should return -EBUSY in this case
>> rather than always return 1 which could confuse the user.
>>
>> Fixes: e8db67eb0ded ("mm: migrate: move_pages() supports thp migration")
>> Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
>> Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
>> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
>> ---
>> mm/migrate.c | 6 ++----
>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index 381963231a62..044656a14ae2 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1632,10 +1632,8 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
>> goto out_putpage;
>>
>> if (PageHuge(page)) {
>> - if (PageHead(page)) {
>> - isolate_huge_page(page, pagelist);
>> - err = 1;
>> - }
>> + if (PageHead(page))
>> + err = isolate_huge_page(page, pagelist) ? 1 : -EBUSY;
>
> I think a:
>
> err = isolate_huge_page(page, pagelist);
> if (!err)
> err = 1;
Many thanks for your comment. IIUC, isolate_huge_page does not return the wanted error code. So the
above code won't do the right thing.
Thanks.
>
> would be a lot more readable here.
>
> .
>
