Re: [PATCH net-next 1/9] netmem: introduce struct netmem_desc mirroring struct page

[Mina Almasry <almasrymina@google.com>]

On Mon, Jun 9, 2025 at 12:32 PM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Mon,  9 Jun 2025 13:32:17 +0900 Byungchul Park wrote:
> > To simplify struct page, the page pool members of struct page should be
> > moved to other, allowing these members to be removed from struct page.
> >
> > Introduce a network memory descriptor to store the members, struct
> > netmem_desc, and make it union'ed with the existing fields in struct
> > net_iov, allowing to organize the fields of struct net_iov.
>
> What's the intended relation between the types?
>
> netmem_ref exists to clearly indicate that memory may not be readable.
> Majority of memory we expect to allocate from page pool must be
> kernel-readable. What's the plan for reading the "single pointer"
> memory within the kernel?
>
> I think you're approaching this problem from the easiest and least
> relevant direction. Are you coordinating with David Howells?

FWIW I did point David to this work in a tangentially related thread:

https://lore.kernel.org/netdev/CAHS8izMMU8QZrvXRiDjqwsBg_34s+dhvSyrU7XGMBuPF6eWyTA@mail.gmail.com/

I think yes it would be good to get a reviewed-by or acked-by from
Matthew or David to show that this approach is in line with their
plans?

From my end I tried to review to:

1. Make sure the changes are compatible with net_iov/netmem_ref.
2. Make sure what's implemented here is in line with the memdesc
effort Matthew lists here[1]. In particular the netmem_desc struct
introduced here is very similar to the zpdesc and ptdesc structs
mentioned as an example in [1].

[1] https://kernelnewbies.org/MatthewWilcox/Memdescs/Path

-- 
Thanks,
Mina