Re: [PATCH net-next] selftests: net: Add a missing config option

[Paolo Abeni <pabeni@redhat.com>]

On 7/29/26 10:44 PM, Alice Mikityanska wrote:
> On Mon, 27 Jul 2026 at 12:09, Matthieu Baerts <matttbe@kernel.org> wrote:
>> On 23/07/2026 16:02, Alice Mikityanska wrote:
>>> From: Alice Mikityanska <alice@isovalent.com>
>>>
>>> Commit 5cb53743e1ff ("selftests: net: Add a test for BIG TCP in UDP
>>> tunnels") used iptables match comment, which was missed from the CI
>>> kernel config. Add the missing config option.
>>
>> It helps, the CI can now run this test!
>>
>> Reviewed-by: Matthieu Baerts <matttbe@kernel.org>
>>
>>
>> But I think another follow-up patch is required, because this test is
>> flaky when using a debug kernel config:
>>
>>
>> https://netdev.bots.linux.dev/flakes.html?min-flip=0&tn-needle=big-tcp-tunnels-sh
>>
>> Maybe because wait_local_port_listen() is required after having called
>> netserver?
> 
> The issue is hard to reproduce on my machine, but I could reproduce it
> in ~12 hours of non-stop testing in a loop. It reproduces even with
> wait_local_port_listen, so it must be something else. The log above
> (and my repro attempts) shows that it fails in a non-first test, but
> netserver starts only once, before the first test. If the failure was
> due to netserver not being ready, it would fail in the first test.
> I'll keep investigating.
I *think* this kind of flakes are sort of expected for 'performance'
related tests when running on debug kernel: the environment can be
painful slow, and few failed iterations I saw has csum offload disabled
- even lower expected tput.

AFAICS the target packet number is independent from KSFT_MACHINE_SLOW
and the actual offload setting. Possibly you can tune the target value a
bit WRT the mentioned variables or skip entirely pkts number validation
in the slowest permutation (note that the self-test will still have some
value due to code coverage with sanitizers enabled).

/p