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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Felix Fietkau , netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220808173939.193804-1-sbodomerle@gmail.com> From: Florian Fainelli In-Reply-To: <20220808173939.193804-1-sbodomerle@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,NICE_REPLY_A, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/8/22 10:39, Sandor Bodo-Merle wrote: > On one of our machines we got: > > kernel BUG at lib/dynamic_queue_limits.c:27!\r\n > Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM\r\n > CPU: 0 PID: 1166 Comm: irq/41-bgmac Tainted: G W O 4.14.275-rt132 #1\r\n > Hardware name: BRCM XGS iProc\r\n > task: ee3415c0 task.stack: ee32a000\r\n > PC is at dql_completed+0x168/0x178\r\n > LR is at bgmac_poll+0x18c/0x6d8\r\n > pc : [] lr : [] psr: 800a0313\r\n > sp : ee32be14 ip : 000005ea fp : 00000bd4\r\n > r10: ee558500 r9 : c0116298 r8 : 00000002\r\n > r7 : 00000000 r6 : ef128810 r5 : 01993267 r4 : 01993851\r\n > r3 : ee558000 r2 : 000070e1 r1 : 00000bd4 r0 : ee52c180\r\n > Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none\r\n > Control: 12c5387d Table: 8e88c04a DAC: 00000051\r\n > Process irq/41-bgmac (pid: 1166, stack limit = 0xee32a210)\r\n > Stack: (0xee32be14 to 0xee32c000)\r\n > be00: ee558520 ee52c100 ef128810\r\n > be20: 00000000 00000002 c0116298 c04b5a18 00000000 c0a0c8c4 c0951780 00000040\r\n > be40: c0701780 ee558500 ee55d520 ef05b340 ef6f9780 ee558520 00000001 00000040\r\n > be60: ffffe000 c0a56878 ef6fa040 c0952040 0000012c c0528744 ef6f97b0 fffcfb6a\r\n > be80: c0a04104 2eda8000 c0a0c4ec c0a0d368 ee32bf44 c0153534 ee32be98 ee32be98\r\n > bea0: ee32bea0 ee32bea0 ee32bea8 ee32bea8 00000000 c01462e4 ffffe000 ef6f22a8\r\n > bec0: ffffe000 00000008 ee32bee4 c0147430 ffffe000 c094a2a8 00000003 ffffe000\r\n > bee0: c0a54528 00208040 0000000c c0a0c8c4 c0a65980 c0124d3c 00000008 ee558520\r\n > bf00: c094a23c c0a02080 00000000 c07a9910 ef136970 ef136970 ee30a440 ef136900\r\n > bf20: ee30a440 00000001 ef136900 ee30a440 c016d990 00000000 c0108db0 c012500c\r\n > bf40: ef136900 c016da14 ee30a464 ffffe000 00000001 c016dd14 00000000 c016db28\r\n > bf60: ffffe000 ee21a080 ee30a400 00000000 ee32a000 ee30a440 c016dbfc ee25fd70\r\n > bf80: ee21a09c c013edcc ee32a000 ee30a400 c013ec7c 00000000 00000000 00000000\r\n > bfa0: 00000000 00000000 00000000 c0108470 00000000 00000000 00000000 00000000\r\n > bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000\r\n > bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000\r\n > [] (dql_completed) from [] (bgmac_poll+0x18c/0x6d8)\r\n > [] (bgmac_poll) from [] (net_rx_action+0x1c4/0x494)\r\n > [] (net_rx_action) from [] (do_current_softirqs+0x1ec/0x43c)\r\n > [] (do_current_softirqs) from [] (__local_bh_enable+0x80/0x98)\r\n > [] (__local_bh_enable) from [] (irq_forced_thread_fn+0x84/0x98)\r\n > [] (irq_forced_thread_fn) from [] (irq_thread+0x118/0x1c0)\r\n > [] (irq_thread) from [] (kthread+0x150/0x158)\r\n > [] (kthread) from [] (ret_from_fork+0x14/0x24)\r\n > Code: a83f15e0 0200001a 0630a0e1 c3ffffea (f201f0e7) \r\n > > The issue seems similar to commit 90b3b339364c ("net: hisilicon: Fix a BUG > trigered by wrong bytes_compl") and potentially introduced by commit > b38c83dd0866 ("bgmac: simplify tx ring index handling"). > > If there is an RX interrupt between setting ring->end > and netdev_sent_queue() we can hit the BUG_ON as bgmac_dma_tx_free() > can miscalculate the queue size while called from bgmac_poll(). > > The machine which triggered the BUG runs a v4.14 RT kernel - but the issue > seems present in mainline too. > > Fixes: b38c83dd0866 ("bgmac: simplify tx ring index handling") > Signed-off-by: Sandor Bodo-Merle Reviewed-by: Florian Fainelli Thanks! -- Florian