netdev - Re: BUG: kernel NULL pointer dereference in __cgroup_bpf_run_filter

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Date:   Sun, 14 Jun 2020 11:29:34 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Daniël Sonck <dsonck92@...il.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: BUG: kernel NULL pointer dereference in __cgroup_bpf_run_filter_skb

Hello,

On Sun, Jun 14, 2020 at 5:39 AM Daniël Sonck <dsonck92@...il.com> wrote:
>
> Hello,
>
> I found on the archive that this bug I encountered also happened to
> others. I too have a very similar stacktrace. The issue I'm
> experiencing is:
>
> Whenever I fully boot my cluster, in some time, the host crashes with
> the __cgroup_bpf_run_filter_skb NULL pointer dereference. This has
> been sporadic enough before not to cause real issues. However, as of
> lately, the bug is triggered much more frequently. I've changed my
> server hardware so I could capture serial output in order to get the
> trace. This trace looked very similar as reported by Lu Fengqi. As it
> currently stands, I cannot run the cluster as it's almost instantly
> crashing the host.

This has been reported for multiple times. Are you able to test the
attached patch? And let me know if everything goes fine with it.

I suspect we may still leak some cgroup refcnt even with the patch,
but it might be much harder to trigger with this patch applied.

Thanks.

View attachment "cgroup_sk_alloc.diff" of type "text/x-patch" (614 bytes)