Re: [PATCH RFC 25/29] mm: simplify folio_expected_ref_count()

[Zi Yan]

On 18 Jun 2025, at 13:40, David Hildenbrand wrote:

> Now that PAGE_MAPPING_MOVABLE is gone, we can simplify and rely on the
> folio_test_anon() test only.
>
> ... but staring at the users, this function should never even have been
> called on movable_ops pages. E.g.,
> * __buffer_migrate_folio() does not make sense for them
> * folio_migrate_mapping() does not make sense for them
> * migrate_huge_page_move_mapping() does not make sense for them
> * __migrate_folio() does not make sense for them
> * ... and khugepaged should never stumble over them
>
> Let's simply refuse typed pages (which includes slab) except hugetlb,
> and WARN.
>
> Signed-off-by: David Hildenbrand <da...@redhat.com>
> ---
>  include/linux/mm.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
Reviewed-by: Zi Yan <z...@nvidia.com>
--
Best Regards,
Yan, Zi