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Date:   Fri, 1 Jul 2022 22:01:10 +0200
From:   Florian Westphal <fw@strlen.de>
To:     Kajetan Puchalski <kajetan.puchalski@arm.com>
Cc:     Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@netfilter.org>,
        Florian Westphal <fw@strlen.de>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, Mel Gorman <mgorman@suse.de>,
        lukasz.luba@arm.com, dietmar.eggemann@arm.com,
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        regressions@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [Regression] stress-ng udp-flood causes kernel panic on Ampere
 Altra
Message-ID: <20220701200110.GA15144@breakpoint.cc>
References: <Yr7WTfd6AVTQkLjI@e126311.manchester.arm.com>
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Kajetan Puchalski <kajetan.puchalski@arm.com> wrote:
> While running the udp-flood test from stress-ng on Ampere Altra (Mt.
> Jade platform) I encountered a kernel panic caused by NULL pointer
> dereference within nf_conntrack.
> 
> The issue is present in the latest mainline (5.19-rc4), latest stable
> (5.18.8), as well as multiple older stable versions. The last working
> stable version I found was 5.15.40.

Do I need a special setup for conntrack?

No crashes after more than one hour of stress-ng on
1. 4 core amd64 Fedora 5.17 kernel
2. 16 core amd64, linux stable 5.17.15
3. 12 core intel, Fedora 5.18 kernel
4. 3 core aarch64 vm, 5.18.7-200.fc36.aarch64

I used standard firewalld ruleset for all of these and manually tuned
conntrack settings to make sure the early evict path (as per backtrace)
gets exercised.