From: Jakub Kicinski <kuba@kernel.org>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jiri Olsa <olsajiri@gmail.com>, Yonghong Song <yhs@meta.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Song Liu <song@kernel.org>, Hao Sun <sunhao.th@gmail.com>,
Peter Zijlstra <peterz@infradead.org>, bpf <bpf@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Yonghong Song <yhs@fb.com>, KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
David Miller <davem@davemloft.net>,
Jesper Dangaard Brouer <hawk@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
Thorsten Leemhuis <regressions@leemhuis.info>
Subject: Re: BUG: unable to handle kernel paging request in bpf_dispatcher_xdp
Date: Fri, 9 Dec 2022 15:34:45 -0800 [thread overview]
Message-ID: <20221209153445.22182ca5@kernel.org> (raw)
In-Reply-To: <96b0d9d8-02a7-ce70-de1e-b275a01f5ff3@iogearbox.net>
On Sat, 10 Dec 2022 00:32:07 +0100 Daniel Borkmann wrote:
> fwiw, these should not be necessary, Documentation/RCU/checklist.rst :
>
> [...] One example of non-obvious pairing is the XDP feature in networking,
> which calls BPF programs from network-driver NAPI (softirq) context. BPF
> relies heavily on RCU protection for its data structures, but because the
> BPF program invocation happens entirely within a single local_bh_disable()
> section in a NAPI poll cycle, this usage is safe. The reason that this usage
> is safe is that readers can use anything that disables BH when updaters use
> call_rcu() or synchronize_rcu(). [...]
FWIW I sent a link to the thread to Paul and he confirmed
the RCU will wait for just the BH.
next prev parent reply other threads:[~2022-12-09 23:34 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-06 3:28 BUG: unable to handle kernel paging request in bpf_dispatcher_xdp Hao Sun
2022-12-06 6:46 ` Hao Sun
2022-12-06 15:18 ` Jiri Olsa
2022-12-07 19:57 ` Alexei Starovoitov
2022-12-08 17:48 ` Alexei Starovoitov
2022-12-08 18:06 ` Jiri Olsa
2022-12-08 22:26 ` Jiri Olsa
2022-12-08 23:02 ` Jiri Olsa
2022-12-09 7:09 ` Jiri Olsa
2022-12-09 11:22 ` Jiri Olsa
2022-12-09 13:50 ` Jiri Olsa
2022-12-09 15:20 ` Jiri Olsa
2022-12-09 20:31 ` Yonghong Song
2022-12-09 21:53 ` Jiri Olsa
2022-12-09 22:41 ` Daniel Borkmann
2022-12-09 23:07 ` Jiri Olsa
2022-12-09 23:29 ` Jiri Olsa
2022-12-09 23:32 ` Daniel Borkmann
2022-12-09 23:34 ` Jakub Kicinski [this message]
2022-12-10 0:06 ` Jiri Olsa
2022-12-10 0:38 ` Paul E. McKenney
2022-12-10 13:05 ` Jiri Olsa
2022-12-10 1:12 ` Alexei Starovoitov
2022-12-10 13:11 ` Jiri Olsa
2022-12-12 15:04 ` Jiri Olsa
2022-12-13 2:26 ` Hao Sun
2022-12-08 8:44 ` BUG: unable to handle kernel paging request in bpf_dispatcher_xdp #forregzbot Thorsten Leemhuis
2022-12-19 9:59 ` Thorsten Leemhuis
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