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Rozycki" Cc: Thomas Bogendoerfer , Jiaxun Yang , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, Huacai Chen References: <20260409164846.3176046-2-stefan.wiehler@nokia.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: FR4P281CA0003.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:c8::14) To PAWPR07MB9688.eurprd07.prod.outlook.com (2603:10a6:102:383::17) Precedence: bulk X-Mailing-List: linux-mips@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PAWPR07MB9688:EE_|AS8PR07MB7799:EE_ X-MS-Office365-Filtering-Correlation-Id: 836fcfe9-d8dd-41ef-efbc-08dea0690153 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|376014|22082099003|56012099003|18002099003; X-Microsoft-Antispam-Message-Info: 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=?utf-8?B?ZEluWWZzRVZ4QmhNbVdVVXo1R0txOGdOMDFHNi9wcFh1eUdOWG52VWVCcFpn?= =?utf-8?Q?dumvOPNKMVvrglTQ=3D?= X-OriginatorOrg: nokia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 836fcfe9-d8dd-41ef-efbc-08dea0690153 X-MS-Exchange-CrossTenant-AuthSource: PAWPR07MB9688.eurprd07.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Apr 2026 12:16:38.9766 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 5d471751-9675-428d-917b-70f44f9630b0 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: jQEFKu00JG/PrC5H5QP1RhWOOm80QCpYhkwtO3I6aRd2zyMftwiRwUQ7qxj+lH6pDBZuXM+F/I6SvPKxaAaZmG9d4LV+/5CkS3MWywnZVig= X-MS-Exchange-Transport-CrossTenantHeadersStamped: AS8PR07MB7799 Hi Maciej, > I was able to reproduce this splat on latest mainline with the attached > defconfig on QEMU, which I invoked as follows: > > $ qemu-system-mips64 -cpu I6400 -smp 2 -kernel vmlinux -nographic > > ============================= > WARNING: suspicious RCU usage > 7.0.0-rc7-dirty #13 Not tainted > ----------------------------- > kernel/locking/lockdep.c:3801 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > > RCU used illegally from offline CPU! > rcu_scheduler_active = 1, debug_locks = 1 > no locks held by swapper/1/0. > > stack backtrace: > CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 7.0.0-rc7-dirty #13 VOLUNTARY > Hardware name: mti,malta > Stack : a8000000021fb938 0000000000000000 0000000000000018 a8000000021fb888 > a8000000021fb888 a8000000021fb9b8 0000000000000000 0000000000000000 > 00f87412b0603bdf 0000000000000001 0000000000000000 0000000000000000 > ffffffff80f9e5b0 0000000000000000 ffffffff80abb824 000000000000001b > ffffffffffffffff 0000000000000000 0000000000000000 ffffffff80d2ea28 > ffffffff80e10000 ffffffff80ccf9e0 0000000000000001 0000000000000000 > 0000000000000003 0000000000000000 a8000000021fb680 0000000030400080 > 0000000000000000 a8000000021f8000 a8000000021fb880 ffffffff80f00000 > ffffffff801190dc 0000000000000000 0000000000000000 0000000000000000 > 0000000000000000 0000000000000000 ffffffff801190f4 00f87412b0603bdf > ... > Call Trace: > [] show_stack+0x5c/0x150 > [] dump_stack_lvl+0xa4/0xe8 > [] lockdep_rcu_suspicious+0x180/0x228 > [] __lock_acquire+0x15b0/0x2b00 > [] lock_acquire+0x144/0x490 > [] _raw_spin_lock_irqsave+0x54/0x88 > [] ___slab_alloc+0x190/0x950 > [] __kmalloc_noprof+0x344/0x520 > [] __alloc_empty_sheaf+0x48/0x78 > [] __pcs_replace_empty_main+0x4ec/0x680 > [] __kmalloc_noprof+0x45c/0x520 > [] r4k_tlb_uniquify+0x58/0x2c8 > [] r4k_tlb_configure+0xb4/0xd0 > [] tlb_init+0xc/0x80 > [] per_cpu_trap_init+0xfc/0x168 > [] start_secondary+0x28/0x118 > [] mips_cps_core_boot+0x74/0x88 > > However, on that platform even before that you will see various Lockdep RCU > splats complaining about taking the console lock from an offline CPU > originating from c-r4k.c; one more reason to call rcutree_report_cpu_starting() > earlier. Have you been able to reproduce the issue with above hints? Kind regards, Stefan