Received-SPF: pass (google.com: domain of linux-kernel+bounces-37143-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Message-ID: <13579588-eb9d-4626-a063-c0b77ed80f11@linux.ibm.com>
Date: Wed, 24 Jan 2024 15:29:26 +0100
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: [REGRESSION] v6.8 SMC-D issues
To: Wen Gu <guwen@linux.alibaba.com>, wenjia@linux.ibm.com, hca@linux.ibm.com,
        gor@linux.ibm.com, agordeev@linux.ibm.com, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
        jaka@linux.ibm.com, Matthew Rosato <mjrosato@linux.ibm.com>
Cc: Linux regressions mailing list <regressions@lists.linux.dev>,
        borntraeger@linux.ibm.com, svens@linux.ibm.com,
        alibuda@linux.alibaba.com, tonylu@linux.alibaba.com,
        raspl@linux.ibm.com, schnelle@linux.ibm.com,
        guangguan.wang@linux.alibaba.com, linux-s390@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Halil Pasic <pasic@linux.ibm.com>
References: <20231219142616.80697-1-guwen@linux.alibaba.com>
 <20231219142616.80697-8-guwen@linux.alibaba.com>
Content-Language: en-US
From: Alexandra Winter <wintera@linux.ibm.com>
In-Reply-To: <20231219142616.80697-8-guwen@linux.alibaba.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit

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>