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

[Toke Høiland-Jørgensen]

Byungchul Park <byungchul@xxxxxx> 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@xxxxxxxxx/
>
> While at it, move the sanity check for page pool to on free.
>
> Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
> Co-developed-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
> Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
> Signed-off-by: Byungchul Park <byungchul@xxxxxx>
> Acked-by: David Hildenbrand <david@xxxxxxxxxx>
> Acked-by: Zi Yan <ziy@xxxxxxxxxx>
> Acked-by: Mina Almasry <almasrymina@xxxxxxxxxx>

Acked-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>

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