Re: [PATCH v2] mm/migrate: rename PAGE_ migration flags to FOLIO_

[Zi Yan]

On 24 Mar 2026, at 7:47, Shivank Garg wrote:

> These flags only track folio-specific state during migration and are
> not used for movable_ops pages. Rename the enum values and the
> old_page_state variable to match.
>
> No functional change.
>
> Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
> Signed-off-by: Shivank Garg <shivankg@xxxxxxx>
> ---
>
> Applies cleanly on mm-new (02b045682c74).
>
> v1: https://lore.kernel.org/all/20260323141935.389232-3-shivankg@xxxxxxx
>
> v2:
> - Rename FOLIO_MF_* to FOLIO_*, per feedback from Willy.
>
>  mm/migrate.c | 46 +++++++++++++++++++++++-----------------------
>  1 file changed, 23 insertions(+), 23 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 05cb408846f2..7dd6c2f2e1ef 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1135,26 +1135,26 @@ static int move_to_new_folio(struct folio *dst, struct folio *src,
>   * This is safe because nobody is using it except us.
>   */
>  enum {
> -	PAGE_WAS_MAPPED = BIT(0),
> -	PAGE_WAS_MLOCKED = BIT(1),
> -	PAGE_OLD_STATES = PAGE_WAS_MAPPED | PAGE_WAS_MLOCKED,
> +	FOLIO_WAS_MAPPED = BIT(0),
> +	FOLIO_WAS_MLOCKED = BIT(1),
> +	FOLIO_OLD_STATES = FOLIO_WAS_MAPPED | FOLIO_WAS_MLOCKED,
>  };
>
>  static void __migrate_folio_record(struct folio *dst,
> -				   int old_page_state,
> +				   int old_folio_state,
>  				   struct anon_vma *anon_vma)
>  {
> -	dst->private = (void *)anon_vma + old_page_state;
> +	dst->private = (void *)anon_vma + old_folio_state;
>  }
>
>  static void __migrate_folio_extract(struct folio *dst,
> -				   int *old_page_state,
> +				   int *old_folio_state,
>  				   struct anon_vma **anon_vmap)
>  {
>  	unsigned long private = (unsigned long)dst->private;
>
> -	*anon_vmap = (struct anon_vma *)(private & ~PAGE_OLD_STATES);
> -	*old_page_state = private & PAGE_OLD_STATES;
> +	*anon_vmap = (struct anon_vma *)(private & ~FOLIO_OLD_STATES);
> +	*old_folio_state = private & FOLIO_OLD_STATES;
>  	dst->private = NULL;
>  }

Just an observation on folio->private, it is void*, but page->private
is unsigned long. It confused me a bit. There are folio_get_private()
and folio_change_private(), I wonder if we want to use them here
instead of direct ->private accesses. Feel free to ignore this,
since it is irrelevant to this patch.

LGTM.

Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>


Best Regards,
Yan, Zi