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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Shuah Khan , Simon Horman , netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next v2 1/2] amt: mark relay data as a UDP tunnel packet before sending it Date: Sun, 4 Oct 2026 17:01:23 +0300 Message-ID: <20261004140123.94341-1-omar@blockcast.net> X-Mailer: git-send-email 2.50.1 In-Reply-To: <179106416186.434549.2202047416681649119@kernel.org> References: <20261002212458.34247-1-omar@blockcast.net> <20261002212458.34247-2-omar@blockcast.net> <179106416186.434549.2202047416681649119@kernel.org> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Sat, Oct 3, 2026, Sashiko wrote: > Should this have a Fixes: tag? No, on purpose. Eric asked for this to go to net-next, since the bug needs a non-default setting: "Note that tx checksum offload is off by default on amt, so the bug would not trigger by default." "A better fix would be (for net-next) to call udp_tunnel_handle_offloads() in amt_send_multicast_data() like other UDP tunnels do" https://lore.kernel.org/all/CAL4Wiiqw_7Mxa5W1EQgw2=KpJNNxG=cBLXsHvpio29GvD1UKZg@mail.gmail.com/ > This is a pre-existing issue, but it is closely related to this patch. I have not reproduced it; so far this comes from reading the code. It would need rx-gro-list on the relay's ingress device, and tx checksumming plus tx-scatter-gather-fraglist on the amt device (all three off by default), and a GRO aggregate that passes ipmr's DF/MTU check. It predates this patch, and the cover letter already lists it as not touched and untested. I will send a separate fix for it once I have reproduced it.