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Message-ID: <896cbaf8-c23d-e51a-6f5e-1e6d0383aed0@linux.dev>
Date:   Wed, 26 Jul 2023 11:16:22 -0700
MIME-Version: 1.0
Subject: Re: [syzbot] [bpf?] WARNING: ODEBUG bug in tcx_uninstall
To:     Leon Romanovsky <leon@kernel.org>, Jakub Kicinski <kuba@kernel.org>
Cc:     Daniel Borkmann <daniel@iogearbox.net>,
        syzbot <syzbot+14736e249bce46091c18@syzkaller.appspotmail.com>,
        andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
        haoluo@google.com, john.fastabend@gmail.com, jolsa@kernel.org,
        kpsingh@kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, sdf@google.com, song@kernel.org,
        syzkaller-bugs@googlegroups.com, yhs@fb.com,
        Gal Pressman <gal@nvidia.com>
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From:   Martin KaFai Lau <martin.lau@linux.dev>
In-Reply-To: <20230726170133.GX11388@unreal>
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On 7/26/23 10:01 AM, Leon Romanovsky wrote:
> On Wed, Jul 26, 2023 at 08:23:12AM -0700, Jakub Kicinski wrote:
>> On Wed, 26 Jul 2023 10:12:54 +0300 Leon Romanovsky wrote:
>>>> Thanks, I'll take a look this evening.
>>>
>>> Did anybody post a fix for that?
>>>
>>> We are experiencing the following kernel panic in netdev commit
>>> b57e0d48b300 (net-next/main) Merge branch '100GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/next-queue
>>
>> Not that I know, looks like this is with Daniel's previous fix already
>> present, and syzbot is hitting it, too :(
> 
> My naive workaround which restored our regression runs is:
> 
> diff --git a/kernel/bpf/tcx.c b/kernel/bpf/tcx.c
> index 69a272712b29..10c9ab830702 100644
> --- a/kernel/bpf/tcx.c
> +++ b/kernel/bpf/tcx.c
> @@ -111,6 +111,7 @@ void tcx_uninstall(struct net_device *dev, bool ingress)
>                          bpf_prog_put(tuple.prog);
>                  tcx_skeys_dec(ingress);
>          }
> -       WARN_ON_ONCE(tcx_entry(entry)->miniq_active);
> +       tcx_miniq_set_active(entry, false);

Thanks for the report. I will look into it.

>          tcx_entry_free(entry);
>   }
>