Hi Konstantin,

On Wed, Jul 09, 2025 at 09:54:03AM -0500, Konstantin Shkolnyy wrote:

I'm seeing a problem on s390 with the new "SOCK_STREAM transport 
change null-ptr-deref" test. Here is how it appears to happen:

test_stream_transport_change_client() spins for 2s and sends 70K+ 
CONTROL_CONTINUE messages to the "control" socket.

test_stream_transport_change_server() spins calling accept() because 
it keeps receiving CONTROL_CONTINUE.

When the client exits, the server has received just under 1K of those 
70K CONTROL_CONTINUE, so it calls accept() again but the client has 
exited, so accept() never returns and the server never exits.

Thanks for pointing this out!
I had an offline discussion with Stefano about this issue.
This patch[1] should address it.
Please let us know if it works on s390 too.

Cheers,
Luigi

[1]https://lore.kernel.org/netdev/20250708111701.129585-1-sgarzare@redhat.com/ (local)