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Date:   Mon, 21 Nov 2022 12:19:55 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     xiangxia.m.yue@gmail.com
Cc:     bpf@vger.kernel.org, netdev@vger.kernel.org,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>
Subject: Re: [net-next] bpf: avoid hashtab deadlock with try_lock
Message-ID: <20221121121939.0e5e2401@kernel.org>
In-Reply-To: <20221121100521.56601-2-xiangxia.m.yue@gmail.com>
References: <20221121100521.56601-1-xiangxia.m.yue@gmail.com>
        <20221121100521.56601-2-xiangxia.m.yue@gmail.com>
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On Mon, 21 Nov 2022 18:05:21 +0800 xiangxia.m.yue@gmail.com wrote:
> From: Tonghao Zhang <xiangxia.m.yue@gmail.com>
> 
> The commit 20b6cc34ea74 ("bpf: Avoid hashtab deadlock with map_locked"),
> try to fix deadlock, but in some case, the deadlock occurs:
> 
> * CPUn in task context with K1, and taking lock.
> * CPUn interrupted by NMI context, with K2.
> * They are using the same bucket, but different map_locked.

You should really put bpf@ in the CC line for bpf patches.