Re: [PATCH v2 7/8] mm: migrate: remove PageHead() check for HugeTLB in add_page_for_migration()

[Zi Yan]

On 21 Aug 2023, at 7:56, Kefeng Wang wrote:

> There is some different between hugeTLB and THP behave when passed the
> address of a tail page, for THP, it will migrate the entire THP page,
> but for HugeTLB, it will return -EACCES, or -ENOENT before commit
> e66f17ff7177 ("mm/hugetlb: take page table lock in follow_huge_pmd()"),
>
>   -EACCES The page is mapped by multiple processes and can be moved
> 	  only if MPOL_MF_MOVE_ALL is specified.
>   -ENOENT The page is not present.
>
> But when check manual[1], both of the two errnos are not suitable, it
> is better to keep the same behave between hugetlb and THP when passed
> the address of a tail page, so let's just remove the PageHead() check
> for HugeTLB.
>
> [1] https://man7.org/linux/man-pages/man2/move_pages.2.html
>
> Suggested-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> ---
>  mm/migrate.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>

Acked-by: Zi Yan <ziy@xxxxxxxxxx>

--
Best Regards,
Yan, Zi

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