linux-kernel - Re: [PATCH] mm, page_pool: introduce a new page type for page pool in page type

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Message-ID: <20250722010326.GA45337@system.software.com>
Date: Tue, 22 Jul 2025 10:03:26 +0900
From: Byungchul Park <byungchul@...com>
To: Pavel Begunkov <asml.silence@...il.com>
Cc: linux-mm@...ck.org, netdev@...r.kernel.org,
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Subject: Re: [PATCH] mm, page_pool: introduce a new page type for page pool
 in page type

On Mon, Jul 21, 2025 at 12:12:39PM +0100, Pavel Begunkov wrote:
> On 7/21/25 06:49, Byungchul Park wrote:
> > Hi,
> > 
> > I focused on converting the existing APIs accessing ->pp_magic field to
> > page type APIs.  However, yes.  Additional works would better be
> > considered on top like:
> > 
> >     1. Adjust how to store and retrieve dma index.  Maybe network guys
> >        can work better on top.
> > 
> >     2. Move the sanity check for page pool in mm/page_alloc.c to on free.
> 
> Don't be in a hurry, I've got a branch, but as mentioned before,
> it'll be for-6.18. And there will also be more time for testing.

I'm not.  I listed the two items above wishing someone to work on it on
top of this patch in the future.

> > This work was inspired by the following link by Pavel:
> 
> The idea came from David, let's add
> 
> Suggested-by: David Hildenbrand <david@...hat.com>

Okay.  I will replace the current one with this.

> ...> -
> >   static inline bool netmem_is_pp(netmem_ref netmem)
> >   {
> > -     return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) == PP_SIGNATURE;
> > +     if (netmem_is_net_iov(netmem))
> 
> This needs to return false for tx niovs. Seems like all callers are
> gated on ->pp_recycle, so maybe it's fine, but we can at least
> check pp. Mina, you've been checking tx doesn't mix with rx, any
> opinion on that?

I will wait for the answer of this before going ahead.

> Question to net maintainers, can a ->pp_recycle marked skb contain
> not page pool originated pages or a mix?

This too.

	Byungchul

> --
> Pavel Begunkov