[PATCH v1 23/29] mm/page-alloc: remove PageMappingFlags()

[Lorenzo Stoakes]

On Mon, Jun 30, 2025 at 03:00:04PM +0200, David Hildenbrand wrote:
> We can now simply check for PageAnon() and remove PageMappingFlags().
>
> ... and while at it, use the folio instead and operate on
> folio->mapping.

Probably worth mentioning to be super crystal clear that this is because
now it's either an anon folio or a KSM folio, both of which set the
FOLIO_MAPPING_ANON flag.

I wonder if there's other places that could be fixed up similarly that do
folio_test_anon() || folio_test_ksm() or equivalent?

>
> Reviewed-by: Zi Yan <ziy at nvidia.com>
> Signed-off-by: David Hildenbrand <david at redhat.com>

LGTM, so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes at oracle.com>


> ---
>  include/linux/page-flags.h | 5 -----
>  mm/page_alloc.c            | 7 +++----
>  2 files changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index abed972e902e1..f539bd5e14200 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -723,11 +723,6 @@ static __always_inline bool folio_mapping_flags(const struct folio *folio)
>  	return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) != 0;
>  }
>
> -static __always_inline bool PageMappingFlags(const struct page *page)
> -{
> -	return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
> -}
> -
>  static __always_inline bool folio_test_anon(const struct folio *folio)
>  {
>  	return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index a134b9fa9520e..a0ebcc5f54bb2 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1375,10 +1375,9 @@ __always_inline bool free_pages_prepare(struct page *page,
>  			(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
>  		}
>  	}
> -	if (PageMappingFlags(page)) {
> -		if (PageAnon(page))
> -			mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1);
> -		page->mapping = NULL;
> +	if (folio_test_anon(folio)) {
> +		mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1);
> +		folio->mapping = NULL;
>  	}
>  	if (unlikely(page_has_type(page)))
>  		page->page_type = UINT_MAX;
> --
> 2.49.0
>