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

Lorenzo Stoakes
2025-07-01T13:09:35Z

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@nvidia.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

LGTM, so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@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
>