Re: [PATCH net v2 1/1] tcp: reject non zerocopy devmem tx

On 9/9/26 16:57, Mina Almasry wrote:

On Wed, Sep 9, 2026 at 6:45 AM [off-list ref] wrote:

...>> so attaching that uarg to a copied page frag in tcp_send_syn_data()

quoted

would leave the frag unaccounted too.

Would it make sense to also reject dmabuf_id together with
MSG_FASTOPEN/DEFER_CONNECT and with repair-queue sends, or to teach
those paths about the binding?  The commit message mentions neither, so
it is hard to tell from the changelog whether these were considered,
which also matters for backporting given the two Fixes: tags.

Yes, I think we'd need to exclude MSG_FASTOPEN and DEFER_CONNECT.
Those are set by the userspace right? So it doesn't matter much if we
don't support them with devmem. Not sure how to correctly exclude
repair-queue sends.

I don't know any other user of socket repair apart from CRIU,
and devmem + CRIU is quite a narrow use case, I doubt they yet
do that, and IIRC they don't support restoring any of the
GPUs state for it to be useful. IOW, failing repair with devmem
payload sounds like an option.

I guess it's pointing to more pre-existing issues :( But this patch on
its own is fine.

Reviewed-by: Mina Almasry <redacted>

Thanks

I can try to follow up on the other prexisting issues.

Great, then I'll leave it to you

-- 
Pavel Begunkov