Received-SPF: pass (google.com: domain of linux-kernel+bounces-33977-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:40f1:3f00::1 as permitted sender) client-ip=2604:1380:40f1:3f00::1;
Message-ID: <f96b33ab-56d5-4a43-a1ff-2e68e2c55ac2@kernel.org>
Date: Mon, 22 Jan 2024 19:22:42 +0100
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: Kernel panic in netif_rx_internal after v6 pings between netns
Content-Language: en-GB, fr-BE
To: Jakub Kicinski <kuba@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>, Netdev <netdev@vger.kernel.org>,
 LKML <linux-kernel@vger.kernel.org>
References: <98724dcd-ddf3-4f78-a386-f966ffbc9528@kernel.org>
 <CANn89iLAYXpRiGaGi+rvOZyxMfpUmW2cOg6hLhqE=+2JJS8rkw@mail.gmail.com>
 <65c4f6a2-207f-45e0-9ec3-bad81a05b196@kernel.org>
 <5340b60d-a09a-4865-a648-d1a45e9e6d5f@kernel.org>
 <20240122092804.3535b652@kernel.org>
From: Matthieu Baerts <matttbe@kernel.org>
Autocrypt: addr=matttbe@kernel.org; keydata=
 xsFNBFXj+ekBEADxVr99p2guPcqHFeI/JcFxls6KibzyZD5TQTyfuYlzEp7C7A9swoK5iCvf
 YBNdx5Xl74NLSgx6y/1NiMQGuKeu+2BmtnkiGxBNanfXcnl4L4Lzz+iXBvvbtCbynnnqDDqU
 c7SPFMpMesgpcu1xFt0F6bcxE+0ojRtSCZ5HDElKlHJNYtD1uwY4UYVGWUGCF/+cY1YLmtfb
 WdNb/SFo+Mp0HItfBC12qtDIXYvbfNUGVnA5jXeWMEyYhSNktLnpDL2gBUCsdbkov5VjiOX7
 CRTkX0UgNWRjyFZwThaZADEvAOo12M5uSBk7h07yJ97gqvBtcx45IsJwfUJE4hy8qZqsA62A
 nTRflBvp647IXAiCcwWsEgE5AXKwA3aL6dcpVR17JXJ6nwHHnslVi8WesiqzUI9sbO/hXeXw
 TDSB+YhErbNOxvHqCzZEnGAAFf6ges26fRVyuU119AzO40sjdLV0l6LE7GshddyazWZf0iac
 nEhX9NKxGnuhMu5SXmo2poIQttJuYAvTVUNwQVEx/0yY5xmiuyqvXa+XT7NKJkOZSiAPlNt6
 VffjgOP62S7M9wDShUghN3F7CPOrrRsOHWO/l6I/qJdUMW+MHSFYPfYiFXoLUZyPvNVCYSgs
 3oQaFhHapq1f345XBtfG3fOYp1K2wTXd4ThFraTLl8PHxCn4ywARAQABzSRNYXR0aGlldSBC
 YWVydHMgPG1hdHR0YmVAa2VybmVsLm9yZz7CwZEEEwEIADsCGwMFCwkIBwIGFQoJCAsCBBYC
 AwECHgECF4AWIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZUDpDAIZAQAKCRD2t4JPQmmgcz33
 EACjROM3nj9FGclR5AlyPUbAq/txEX7E0EFQCDtdLPrjBcLAoaYJIQUV8IDCcPjZMJy2ADp7
 /zSwYba2rE2C9vRgjXZJNt21mySvKnnkPbNQGkNRl3TZAinO1Ddq3fp2c/GmYaW1NWFSfOmw
 MvB5CJaN0UK5l0/drnaA6Hxsu62V5UnpvxWgexqDuo0wfpEeP1PEqMNzyiVPvJ8bJxgM8qoC
 cpXLp1Rq/jq7pbUycY8GeYw2j+FVZJHlhL0w0Zm9CFHThHxRAm1tsIPc+oTorx7haXP+nN0J
 iqBXVAxLK2KxrHtMygim50xk2QpUotWYfZpRRv8dMygEPIB3f1Vi5JMwP4M47NZNdpqVkHrm
 jvcNuLfDgf/vqUvuXs2eA2/BkIHcOuAAbsvreX1WX1rTHmx5ud3OhsWQQRVL2rt+0p1DpROI
 3Ob8F78W5rKr4HYvjX2Inpy3WahAm7FzUY184OyfPO/2zadKCqg8n01mWA9PXxs84bFEV2mP
 VzC5j6K8U3RNA6cb9bpE5bzXut6T2gxj6j+7TsgMQFhbyH/tZgpDjWvAiPZHb3sV29t8XaOF
 BwzqiI2AEkiWMySiHwCCMsIH9WUH7r7vpwROko89Tk+InpEbiphPjd7qAkyJ+tNIEWd1+MlX
 ZPtOaFLVHhLQ3PLFLkrU3+Yi3tXqpvLE3gO3LM7BTQRV4/npARAA5+u/Sx1n9anIqcgHpA7l
 5SUCP1e/qF7n5DK8LiM10gYglgY0XHOBi0S7vHppH8hrtpizx+7t5DBdPJgVtR6SilyK0/mp
 9nWHDhc9rwU3KmHYgFFsnX58eEmZxz2qsIY8juFor5r7kpcM5dRR9aB+HjlOOJJgyDxcJTwM
 1ey4L/79P72wuXRhMibN14SX6TZzf+/XIOrM6TsULVJEIv1+NdczQbs6pBTpEK/G2apME7vf
 mjTsZU26Ezn+LDMX16lHTmIJi7Hlh7eifCGGM+g/AlDV6aWKFS+sBbwy+YoS0Zc3Yz8zrdbi
 Kzn3kbKd+99//mysSVsHaekQYyVvO0KD2KPKBs1S/ImrBb6XecqxGy/y/3HWHdngGEY2v2IP
 Qox7mAPznyKyXEfG+0rrVseZSEssKmY01IsgwwbmN9ZcqUKYNhjv67WMX7tNwiVbSrGLZoqf
 Xlgw4aAdnIMQyTW8nE6hH/Iwqay4S2str4HZtWwyWLitk7N+e+vxuK5qto4AxtB7VdimvKUs
 x6kQO5F3YWcC3vCXCgPwyV8133+fIR2L81R1L1q3swaEuh95vWj6iskxeNWSTyFAVKYYVskG
 V+OTtB71P1XCnb6AJCW9cKpC25+zxQqD2Zy0dK3u2RuKErajKBa/YWzuSaKAOkneFxG3LJIv
 Hl7iqPF+JDCjB5sAEQEAAcLBXwQYAQIACQUCVeP56QIbDAAKCRD2t4JPQmmgc5VnD/9YgbCr
 HR1FbMbm7td54UrYvZV/i7m3dIQNXK2e+Cbv5PXf19ce3XluaE+wA8D+vnIW5mbAAiojt3Mb
 6p0WJS3QzbObzHNgAp3zy/L4lXwc6WW5vnpWAzqXFHP8D9PTpqvBALbXqL06smP47JqbyQxj
 Xf7D2rrPeIqbYmVY9da1KzMOVf3gReazYa89zZSdVkMojfWsbq05zwYU+SCWS3NiyF6QghbW
 voxbFwX1i/0xRwJiX9NNbRj1huVKQuS4W7rbWA87TrVQPXUAdkyd7FRYICNW+0gddysIwPoa
 KrLfx3Ba6Rpx0JznbrVOtXlihjl4KV8mtOPjYDY9u+8x412xXnlGl6AC4HLu2F3ECkamY4G6
 UxejX+E6vW6Xe4n7H+rEX5UFgPRdYkS1TA/X3nMen9bouxNsvIJv7C6adZmMHqu/2azX7S7I
 vrxxySzOw9GxjoVTuzWMKWpDGP8n71IFeOot8JuPZtJ8omz+DZel+WCNZMVdVNLPOd5frqOv
 mpz0VhFAlNTjU1Vy0CnuxX3AM51J8dpdNyG0S8rADh6C8AKCDOfUstpq28/6oTaQv7QZdge0
 JY6dglzGKnCi/zsmp2+1w559frz4+IC7j/igvJGX4KDDKUs0mlld8J2u2sBXv7CGxdzQoHaz
 lzVbFe7fduHbABmYz9cefQpO7wDE/Q==
Organization: NGI0 Core
In-Reply-To: <20240122092804.3535b652@kernel.org>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Hi Jakub,

On 22/01/2024 18:28, Jakub Kicinski wrote:

(...)

> Somewhat related. What do you do currently to ignore crashes?

I was wondering why you wanted to ignore crashes :) ... but then I saw
the new "Test ignored" and "Crashes ignored" sections on the status
page. Just to be sure: you don't want to report issues that have not
been introduced by the new patches, right?

We don't need to do that on MPTCP side:
- either it is a new crash with patches that are in reviewed and that's
not impacting others → we test each series individually, not a batch of
series.
- or there are issues with recent patches, not in netdev yet → we fix,
or revert.
- or there is an issue elsewhere, like the kernel panic we reported
here: usually I try to quickly apply a workaround, e.g. applying a fix,
or a revert. I don't think we ever had an issue really impacting us
where we couldn't find a quick solution in one or two days. With the
panic we reported here, ~15% of the tests had an issue, that's "OK" to
have that for a few days/weeks

With fewer tests and a smaller community, it is easier for us to just
say on the ML and weekly meetings: "this is a known issue, please ignore
for the moment". But if possible, I try to add a workaround/fix in our
repo used by the CI and devs (not upstreamed).

For NIPA CI, do you want to do like with the build and compare with a
reference? Or multiple ones to take into account unstable tests? Or
maintain a list of known issues (I think you started to do that,
probably safer/easier for the moment)?

> I was seeing a lot of:
> https://netdev-2.bots.linux.dev/vmksft-net-mp/results/431181/vm-crash-thr0-2
> 
> So I hacked up this function to filter the crash from NIPA CI:
> https://github.com/kuba-moo/nipa/blob/master/contest/remote/lib/vm.py#L50
> It tries to get first 5 function names from the stack, to form 
> a "fingerprint". But I seem to recall a discussion at LPC's testing
> track that there are existing solutions for generating fingerprints.
> Are you aware of any?

No, sorry. But I guess they are using that with syzkaller, no?

I have to admit that crashes (or warnings) are quite rare, so there was
no need to have an automation there. But if it is easy to have a
fingerprint, I will be interested as well, it can help for the tracking:
to find occurrences of crashes/warnings that are very hard to reproduce.

> (FWIW the crash from above seems to be gone on latest linux.git,
> this night's CIs run are crash-free.)

Good it was quickly fixed!

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.