Re: [RFC mm v5 2/2] mm: introduce a new page type for page pool in page type

[Byungchul Park <byungchul@sk.com>]

On Mon, Nov 03, 2025 at 01:26:01PM +0100, Toke Høiland-Jørgensen wrote:
> Byungchul Park <byungchul@sk.com> writes:
> 
> > Currently, the condition 'page->pp_magic == PP_SIGNATURE' is used to
> > determine if a page belongs to a page pool.  However, with the planned
> > removal of ->pp_magic, we should instead leverage the page_type in
> > struct page, such as PGTY_netpp, for this purpose.
> >
> > Introduce and use the page type APIs e.g. PageNetpp(), __SetPageNetpp(),
> > and __ClearPageNetpp() instead, and remove the existing APIs accessing
> > ->pp_magic e.g. page_pool_page_is_pp(), netmem_or_pp_magic(), and
> > netmem_clear_pp_magic().
> >
> > This work was inspired by the following link:
> >
> > [1] https://lore.kernel.org/all/582f41c0-2742-4400-9c81-0d46bf4e8314@gmail.com/
> >
> > While at it, move the sanity check for page pool to on free.
> >
> > Suggested-by: David Hildenbrand <david@redhat.com>
> > Co-developed-by: Pavel Begunkov <asml.silence@gmail.com>
> > Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> > Signed-off-by: Byungchul Park <byungchul@sk.com>
> > Acked-by: David Hildenbrand <david@redhat.com>
> > Acked-by: Zi Yan <ziy@nvidia.com>
> > Acked-by: Mina Almasry <almasrymina@google.com>
> 
> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
> 
> IIUC, this will allow us to move the PP-specific fields out of struct
> page entirely at some point, right? What are the steps needed to get to
> that point after this?

Yes, it'd be almost done once this set gets merged :-)

Will check if I can safely remove pp fields from struct page, and do it!

	Byungchul
> 
> -Toke