Re: [PATCH net-next 4/7] net: devmem: add a per-device netmem TX frag size limit

[Mina Almasry]

On Mon, Nov 2, 2026 at 11:14 AM Stanislav Fomichev <sdf.kernel@xxxxxxxxx> wrote:
>
> Devmem TX frags are bounded only by the net_iov size, which is about
> to grow up to 2MB, more than some devices can describe in a single TX
> descriptor.
>
> Add netmem_tx_max_frag_size, U32_MAX by default, and cap devmem TX
> frags to the limit of the device the binding is attached to.
>
> Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxxx>

Abstractly LGTM but I'm not sure why this is TX-specific. Didn't we
add non-PAGE_SIZE rx net-iovs? This should have been a problem then.
Either you know what you're doing (maybe document in the commit
message) or we need some more alignment on RX and TX.

TBH I was dissapointed when LLMs started reporting that
binding->vdev/dev are treated very differently for RX and TX and I
have to write a cleanup that consolidates this:

https://github.com/mina/linux/compare/devmem-teardown-v4...devmem-lease-bind-map-dev

I think maybe my reviews and yours maybe should be more mindful about
keeping these memory things consolidated and as much as possible not
RX/TX specific.

-- 
Thanks,
Mina