Hi Paolo,

On Fri, 2025-10-10 at 20:22 +0800, Geliang Tang wrote:
> Hi Paolo,
> 
> On Fri, 2025-10-10 at 10:21 +0200, Paolo Abeni wrote:
> > On 10/9/25 3:58 PM, Paolo Abeni wrote:
> > > @Geliang: if you reproduce the issue multiple times, are there
> > > any
> > > common patterns ? i.e. sender files considerably larger than the
> > > client
> > > one, or only a specific subsets of all the test-cases failing, or
> > > ...
> > 
> > Other questions:
> > - Can you please share your setup details (VM vs baremetal, debug
> > config
> > vs non debug, vmg vs plain qemu, number of [v]cores...)? I can't
> > repro
> > the issue locally.
> 
> Here are my modifications:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/geliang/mptcp_net-next.git/log/?h=splice_new
> 
> I used mptcp-upstream-virtme-docker normal config to reproduce it:
> 
> docker run \
> 	-e INPUT_NO_BLOCK=1 \
> 	-e INPUT_PACKETDRILL_NO_SYNC=1 \
> 	-v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
>         --pull always ghcr.io/multipath-tcp/mptcp-upstream-virtme-
> docker:latest \
> 	auto-normal
> 
> $ cat .virtme-exec-run 
> run_loop run_selftest_one ./mptcp_connect_splice.sh
> 
> Running mptcp_connect_splice.sh in a loop dozens of times should
> reproduce the test failure.
> 
> > - Can you please share a pcap capture _and_ the selftest text
> > output
> > for
> > the same failing  test?

The pcap captures (gQQ13x-ns1-ns3-MPTCP-MPTCP-dead:beef:3::2-10013-
connector.pcap, gQQ13x-ns1-ns3-MPTCP-MPTCP-dead:beef:3::2-10013-
listener.pcap) and the selftest text output (selftest_output) are
attached.

Thanks,
-Geliang

> > 
> > In the log shared previously the sender had data queued at the
> > mptcp-level, but not at TCP-level. In the shared pcap capture the
> > receiver sends a couple of acks opening the tcp-level and mptcp-
> > level
> > window, but the sender never replies.
> > 
> > In such scenario the incoming ack should reach ack_update_msk() ->
> > __mptcp_check_push() -> __mptcp_subflow_push_pending() (or
> > mptcp_release_cb -> __mptcp_push_pending() ) ->
> > mptcp_sendmsg_frag()
> > but
> > such chain is apparently broken somewhere in the failing scenario.
> > Could
> > you please add probe points the the mentioned funtions and perf
> > record
> > the test, to try to see where the mentioned chain is interrupted?
> 
> Thank you for your suggestion. I will proceed with testing
> accordingly.
> 
> -Geliang
> 
> > 
> > Thanks,
> > 
> > Paolo
> > 
> 
>