Miaohe Lin <linmiaohe@xxxxxxxxxx> writes:
> On 2022/3/7 13:07, Huang, Ying wrote:
>> Miaohe Lin <linmiaohe@xxxxxxxxxx> writes:
>>
>>> We should return errno (-EBUSY here) when failed to isolate the huge page
>>> rather than always return 1 which could confuse the user.
>>>
>>> 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 6c2dfed2ddb8..279940c0c064 100644
>>> --- a/mm/migrate.c
>>> +++ b/mm/migrate.c
>>> @@ -1618,10 +1618,8 @@ 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;
>>
>> IMHO, it's better to determine the proper errno inside
>> isolate_huge_page() instead of in the caller. If you think it's
>> necessary to get errno here. How about change isolate_huge_page()
>> instead?
>
> IMO, -EBUSY should be enough for the user (as they could not do much) and this
> errno keeps consistent with the non-hugetlb page case. What do you think?
I found the prototype of isolate_lru_page() is as follows,
int isolate_lru_page(struct page *page)
And it will return errno directly. I think we should follow same
convention here?
Best Regards,
Huang, Ying
