linux-kernel - Re: POSSIBLE BUG: selftests/net/fcnal-test.sh: [FAIL][FIX TESTED] in vrf "bind

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Message-ID: <2d129924-d8c7-0aab-2766-950042b7a801@alu.unizg.hr>
Date:   Thu, 15 Jun 2023 22:10:42 +0200
From:   Mirsad Goran Todorovac <mirsad.todorovac@....unizg.hr>
To:     Guillaume Nault <gnault@...hat.com>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Shuah Khan <shuah@...nel.org>,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: POSSIBLE BUG: selftests/net/fcnal-test.sh: [FAIL][FIX TESTED] in
 vrf "bind - ns-B IPv6 LLA" test

On 6/14/23 10:47, Guillaume Nault wrote:
> On Sat, Jun 10, 2023 at 08:04:02PM +0200, Mirsad Goran Todorovac wrote:
>> This also works on the Lenovo IdeaPad 3 Ubuntu 22.10 laptop, but on the AlmaLinux 8.8
>> Lenovo desktop I have a problem:
>>
>> [root@...mtodorov net]# grep FAIL ../fcnal-test-4.log
>> TEST: ping local, VRF bind - ns-A IP                                          [FAIL]
>> TEST: ping local, VRF bind - VRF IP                                           [FAIL]
>> TEST: ping local, device bind - ns-A IP                                       [FAIL]
>> TEST: ping local, VRF bind - ns-A IP                                          [FAIL]
>> TEST: ping local, VRF bind - VRF IP                                           [FAIL]
>> TEST: ping local, device bind - ns-A IP                                       [FAIL]
>> [root@...mtodorov net]#
>>
>> Kernel is the recent one:
>>
>> [root@...mtodorov net]# uname -rms
>> Linux 6.4.0-rc5-testnet-00003-g5b23878f7ed9 x86_64
>> [root@...mtodorov net]#
> 
> Maybe a problem with the ping version used by the distribution.
> You can try "./fcnal-test.sh -t ipv4_ping -p -v" to view the commands
> run and make the script stop when there's a test failure (so that you
> can see the ping output and try your own commands in the testing
> environment).

Thank you for taking the time for the reply. And thanks for the hint.
But I am sort of on ebb tide on this.

It would be good to have the test run on both versions of Linux to test
the actual kernel faults. Maybe pack a version of ping command w the test?
But I cannot deploy too much time in this.

I hope then the upgrade AlmaLinux 8.8 -> 9.x (or CentOS clones in general)
would solve the issue, but it is not guaranteed, and I would lose bisect
to the old kernels. Which is why I do not upgrade to the latest releases
in the first place. :-/

If it is just the AlmaLinux ping, then it is just an exotic distro, but it
is a CentOS clone, so the issue might exist in the more popular Rocky, too.

I am not sure what is the right way to do in this case or I would already
have done it. Presumptuous maybe, but true.

>>>> However, I have a question:
>>>>
>>>> In the ping + "With VRF" section, the tests with net.ipv4.raw_l3mdev_accept=1
>>>> are repeated twice, while "No VRF" section has the versions:
>>>>
>>>> SYSCTL: net.ipv4.raw_l3mdev_accept=0
>>>>
>>>> and
>>>>
>>>> SYSCTL: net.ipv4.raw_l3mdev_accept=1
>>>>
>>>> The same happens with the IPv6 ping tests.
>>>>
>>>> In that case, it could be that we have only 2 actual FAIL cases,
>>>> because the error is reported twice.
>>>>
>>>> Is this intentional?
>>>
>>> I don't know why the non-VRF tests are run once with raw_l3mdev_accept=0
>>> and once with raw_l3mdev_accept=1. Unless I'm missing something, this
>>> option shouldn't affect non-VRF users. Maybe the objective is to make
>>> sure that it really doesn't affect them. David certainly knows better.
>>
>> The problem appears to be that non-VRF tests are being ran with
>> raw_l3mdev_accept={0|1}, while VRF tests w raw_l3mdev_accept={1|1} ...
> 
> The reason the VRF tests run twice is to test both raw and ping sockets
> (using the "net.ipv4.ping_group_range" sysctl). It doesn't seem anyone
> ever intended to run the VRF tests with raw_l3mdev_accept=0.
> 
> Only the non-VRF tests were intended to be tested with
> raw_l3mdev_accept=0 (see commit c032dd8cc7e2 ("selftests: Add ipv4 ping
> tests to fcnal-test")). But I have no idea why.

Well, you are not to blame if it is not documented.

This thing doesn't come out of the testsuite save by prayer and fasting,
I'm afraid ;-)

Best regards,
Mirsad