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Mon, 27 Jul 2026 12:55:36 -0700 (PDT) From: Serhat Kumral To: yanjun.zhu@linux.dev Cc: zyjzyj2000@gmail.com, xiongwm2026@163.com, jgg@ziepe.ca, leon@kernel.org, dsahern@kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, serhatkumral1@gmail.com, syzbot+8c9eede336e3a843750e@syzkaller.appspotmail.com Subject: Re: [RFC PATCH 1/2] RDMA/rxe: drive UDP tunnel socket lifetime from the GID table Date: Mon, 27 Jul 2026 22:55:21 +0300 Message-ID: <20260727195521.34907-1-serhatkumral1@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260726140253.26870-1-serhatkumral1@gmail.com> References: <20260726140253.26870-1-serhatkumral1@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit I was pointed at Weimin Xiong's "RDMA/rxe: Hold netdev reference for transmit skbs" (v3, 20260716055255.157674-1-xiongwm2026@163.com) and tested with it applied. That patch and this series conflict in rxe_notify(). Its hunk carries "rxe_net_del(&rxe->ib_dev);" as a context line, and this series removes that call together with the function, so neither order applies with a plain git apply. I resolved it by keeping both rxe_flush_qps() calls and dropping the rxe_net_del() line: case NETDEV_GOING_DOWN: /* Start draining TX queues before the netdev disappears. */ rxe_flush_qps(rxe); break; case NETDEV_UNREGISTER: rxe_flush_qps(rxe); ib_unregister_device_queued(&rxe->ib_dev); break; If the tree where the crash appears resolves it differently, that difference is worth seeing. Four kernels on f2ec6312bf71, same config and toolchain as before, 120 runs of rxe_rping_between_netns.sh each: f2ec6312bf71 120/120 + this series 120/120 + the netdev reference patch 120/120 + the netdev reference patch + series 120/120 No KASAN report, GPF, Oops, refcount warning, lockdep splat, hung task or RCU stall in any of them. The module symbol tables confirm each kernel carries what it should: rxe_flush_qps only in the two with the netdev reference patch, rxe_add_gid and rxe_del_gid only in the two with this series. Four kernels reporting nothing made me doubt the setup rather than the result, so I checked that it reports faults at all: a deliberate NULL pointer dereference injected into the rxe transmit path, during the same selftest, gives [ 69.131350] Oops: general protection fault, kernel NULL pointer dereference 0x39: 0000 [#1] SMP KASAN NOPTI [ 69.141660] Workqueue: rxe_wq do_work [rdma_rxe] It reaches the console I capture, my filters count it, and the iteration is recorded as failed. From userspace the selftest just hangs. So it still does not reproduce here. thanks, serhat