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

From: Toke Høiland-Jørgensen <[email-masked]>
Date: Mon, 03 Nov 2025 13:26:01 +0100

Byungchul Park <[email-masked]> 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/[email-masked]/
>
> While at it, move the sanity check for page pool to on free.
>
> Suggested-by: David Hildenbrand <[email-masked]>
> Co-developed-by: Pavel Begunkov <[email-masked]>
> Signed-off-by: Pavel Begunkov <[email-masked]>
> Signed-off-by: Byungchul Park <[email-masked]>
> Acked-by: David Hildenbrand <[email-masked]>
> Acked-by: Zi Yan <[email-masked]>
> Acked-by: Mina Almasry <[email-masked]>

Acked-by: Toke Høiland-Jørgensen <[email-masked]>

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?

-Toke