Re: [REGRESSION] v6.8 SMC-D issues

Alexandra Winter
2024-01-24T14:45:08Z

On 24.01.24 15:29, Alexandra Winter wrote:
> 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@linux.ibm.com>
>
>
>

It seems the issue only occurs, when both client and server are on 6.8+
When either side is on an older kernel (6.5.6-300.fc39.s390x in my case),
I don't see the issue.