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[2001:1ae9:1c2:4c00:726e:c10f:8833:ff22]) by smtp.gmail.com with ESMTPSA id c10-20020a17090618aa00b007c07dfb0816sm561499ejf.215.2022.12.09.05.50.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Dec 2022 05:50:58 -0800 (PST) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Fri, 9 Dec 2022 14:50:55 +0100 To: Alexei Starovoitov , Song Liu Cc: Hao Sun , Peter Zijlstra , bpf , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , David Miller , Jakub Kicinski , Jesper Dangaard Brouer , Linux Kernel Mailing List , netdev , Thorsten Leemhuis Subject: Re: BUG: unable to handle kernel paging request in bpf_dispatcher_xdp Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 09, 2022 at 12:22:37PM +0100, Jiri Olsa wrote: SBIP > > > > > > > > > > > > > > I'm trying to understand the severity of the issues and > > > > > > > whether we need to revert that commit asap since the merge window > > > > > > > is about to start. > > > > > > > > > > > > Jiri, Peter, > > > > > > > > > > > > ping. > > > > > > > > > > > > cc-ing Thorsten, since he's tracking it now. > > > > > > > > > > > > The config has CONFIG_X86_KERNEL_IBT=y. > > > > > > Is it related? > > > > > > > > > > sorry for late reply.. I still did not find the reason, > > > > > but I did not try with IBT yet, will test now > > > > > > > > no difference with IBT enabled, can't reproduce the issue > > > > > > > > > > ok, scratch that.. the reproducer got stuck on wifi init :-\ > > > > > > after I fix that I can now reproduce on my local config with > > > IBT enabled or disabled.. it's something else > > > > I'm getting the error also when reverting the static call change, > > looking for good commit, bisecting > > > > I'm getting fail with: > > f0c4d9fc9cc9 (tag: v6.1-rc4) Linux 6.1-rc4 > > > > v6.1-rc1 is ok > > so far I narrowed it down between rc1 and rc3.. bisect got me nowhere so far > > attaching some more logs looking at the code.. how do we ensure that code running through bpf_prog_run_xdp will not get dispatcher image changed while it's being exetuted we use 'the other half' of the image when we add/remove programs, but could bpf_dispatcher_update race with bpf_prog_run_xdp like: cpu 0: cpu 1: bpf_prog_run_xdp ... bpf_dispatcher_xdp_func start exec image at offset 0x0 bpf_dispatcher_update update image at offset 0x800 bpf_dispatcher_update update image at offset 0x0 still in image at offset 0x0 that might explain why I wasn't able to trigger that on bare metal just in qemu jirka