On Mon, Jul 21, 2025 at 4:11 AM Pavel Begunkov <asml.silence@xxxxxxxxx> 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.
>
> > This work was inspired by the following link by Pavel:
>
> The idea came from David, let's add
>
> Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
>
> ...> -
> > 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?
>
> Question to net maintainers, can a ->pp_recycle marked skb contain
> not page pool originated pages or a mix?
>
IIRC last I looked at the code ->pp_recycle technically means it could
be a mix. Technically it means "consider this netmem for pp recycling
when the skb is freed." and non-pp netmems don't get recycled to the
pp obviously, because napi_pp_put_page rejects recycling them.
--
Thanks,
Mina
