Hello Wen Gu, our colleague Matthew reported that SMC-D is failing in certain scenarios on kernel v6.8 (thx Matt!). He bisected it to b40584d ("net/smc: compatible with 128-bits extended GID of virtual ISM device") I think the root cause could also be somewhere else in the SMC-Dv2.1 patchset. I was able to reproduce the issue on a 6.8.0-rc1 kernel. I tested iperf over smc-d with: smc_run iperf3 -s smc_run iperf3 -c <IP@> 1) Doing an iperf in a single system using 127.0.0.1 as IP@ (System A=iperf client=iperf server) 2) Doing iperf to a remote system (System A=client; System B=iperf server) The second iperf fails with an error message like: "iperf3: error - unable to receive cookie at server: Bad file descriptor" on the server" If I do first 2) (iperf to remote) and then 1) (iperf to local), then the iperf to local fails. I can do multiple iperf to the first server without problems. I ran it on a debug server with KASAN, but got no reports in the Logfile. I will try to debug further, but wanted to let you all know. Kind regards Alexandra Reported-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>