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McKenney" CC: , , , Subject: Re: [paulmck-rcu:dev.2023.11.08a] [EXP locktorture] 1254a620b4: WARNING:at_kernel/rcu/tree_stall.h:#rcu_stall_chain_notifier_register Message-ID: References: <202312071506.6eac1bac-oliver.sang@intel.com> <2ad1abcc-d82b-406f-a7b7-606224a24813@paulmck-laptop> <4be82070-4cd5-4f31-8eb4-b38853fad865@paulmck-laptop> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <4be82070-4cd5-4f31-8eb4-b38853fad865@paulmck-laptop> X-ClientProxiedBy: SI2PR01CA0051.apcprd01.prod.exchangelabs.com (2603:1096:4:193::6) To LV3PR11MB8603.namprd11.prod.outlook.com (2603:10b6:408:1b6::9) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LV3PR11MB8603:EE_|CO1PR11MB4947:EE_ X-MS-Office365-Filtering-Correlation-Id: d0a427b9-e732-42d0-5f97-08dbfae61590 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:LV3PR11MB8603.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(7916004)(136003)(376002)(39860400002)(346002)(366004)(396003)(230273577357003)(230173577357003)(230922051799003)(64100799003)(1800799012)(451199024)(186009)(38100700002)(86362001)(82960400001)(316002)(66476007)(66556008)(41300700001)(26005)(33716001)(83380400001)(107886003)(6486002)(9686003)(6512007)(6506007)(6666004)(966005)(2906002)(478600001)(66946007)(6916009)(8936002)(4326008)(44832011)(5660300002)(8676002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?D48sAanrqHU6nPRL8DiSx56PdwYSzrPvPNpDS4LAvc2id4hdDycH7wdJ1bGa?= =?us-ascii?Q?eqUcB9DFAvrQKXd4ibTLqBPXhAmf2Q8Ri0EbqzYBFw4bHl2+vX78oi4jLYPl?= =?us-ascii?Q?wIOOXptzFPU5gTSS1zfOrvGKizZhMU9q7LDyNQjWpkXv1coOokZ42dcxfDmz?= =?us-ascii?Q?rb2hfsIQCbX25D8dlss38v/67fZvAVp0xNxdcaNT4grvBIVF05R1JkCFS4Yo?= =?us-ascii?Q?eIYo7HMYaDyYXbcFboIMMgGyd7B9feidSkoyRH0zCTynNixyE1kZ1pB86kZH?= =?us-ascii?Q?gZ35gRlIqMoyGV0l2FlLn1bWNyZoSHE2JB3tXqCfkirDT1wQsCZyCEtEdcvS?= =?us-ascii?Q?ut50cj68/DGvCsYw9nklIc+rFVIyeaM5kjbBhZMcwa5QLDV65FAUyXj9qza7?= =?us-ascii?Q?k/7A0E2FVEtFh3QPlItetKIRmzU4vyYgGENogJljk05oUDQ4ub20L1dA5jn0?= =?us-ascii?Q?06uohXjGtLNrP+xB44KYHwmTFskdFWkX5NFcg7okNst7Jy8/elX2ufiQWaOr?= =?us-ascii?Q?wSbIyS5WeAAmajCO4gKMdqdgKAKa+VD7ne7vs9TFgP48Cm20dn/sMqbd05BR?= =?us-ascii?Q?J/MIKswiDTA9w+L9VPHlhi7aavZw2RCXECv6h9CpU0VrErZOXblhok0gq9ry?= =?us-ascii?Q?hffRQdJ3aksVAMqKG1emVsXtNF/KlXR2lV7RDd2XqplpKQ3vfrj6lDYwGjow?= =?us-ascii?Q?2Ou0yjsz7qxegCLgcwzQ/ySCU87JDxcM6ykReHJpIAkC09UUoOmE0V4P4EYV?= =?us-ascii?Q?hcFNyxop0efp9I+yi5Tf1BZ/XiQ+jf/I6Ee2KOczupSnk1c1j3xVzqEwQrbU?= =?us-ascii?Q?iIIjwMwdc15PZa3snVM3aW/3oib/ENBLyHaNhs2lkNV19pMgAaTpdSdx08vd?= =?us-ascii?Q?pFQKuhRddyH7lx7iYe9IcIYzI4iEl/iNknDn9ujedklS621XNNCYw9rhWk7e?= =?us-ascii?Q?szJP0z7VbdB6v6fHZuUswiMaih48Laa8Usu56Uu9904TnYTmIKa1innVwalT?= =?us-ascii?Q?/wjIzb2OKNxpmVVUUQETKT8t85g2YJR9sK0GzAro5DdqWw1ObMDYYeAEpZ95?= =?us-ascii?Q?PwSTG0bi74LyURFrkQZN9DZj5wxmrnwmWgjY6IBvL5+6tSqLbDnkCJxW4eww?= =?us-ascii?Q?BhvmUw18HIM+z30+Dvd7+/DtJUi4BHc9kVaE1ze/ge8uLMW/+BnVuGyYrDtP?= =?us-ascii?Q?i5egz6lpvTPR8KxIAv5o8da9HxNbjWgrJKuT/w6V+WoUyJ3nsTFL4/bGZ6Qp?= =?us-ascii?Q?N7K+AqMjn4Fs/DsyG4Ja8ALGgpSGEAnHFDuNw1jFsFlUU7ghW92isIFJghZg?= =?us-ascii?Q?FSGhWeTRIj1bDhKM2MRcK4ehqzDsFmmOre0oHBUspvXln3rAX8e7fC9AKPLI?= =?us-ascii?Q?sfg/BipCz/mOAIwCoVqSg8sBBpiszWlbBe3YmRLSmdI0Gu28s6ZyuMihidZd?= =?us-ascii?Q?Av3a0zTeBY7syvUfabLchs2dad/nHS9gQfRkYfcbHbCJc16ufcCcM+irj5Oi?= =?us-ascii?Q?IxVi3ssPEGbGCJiIA0gL5l9k42/Tcr4Gr+DfdFD9zi+lmkuShqpBXmGrVxAk?= =?us-ascii?Q?EyLYtWQbCNJfoO7MZeZi9xC+dDwBllV1UOGaSzXM0NUcbk1mIRRAaBYqMRkn?= =?us-ascii?Q?Pw=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: d0a427b9-e732-42d0-5f97-08dbfae61590 X-MS-Exchange-CrossTenant-AuthSource: LV3PR11MB8603.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Dec 2023 07:43:51.5159 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 06nagDYc47nEKL+yKHXXHCmMdIjq0RHndjdJbs5NDlmlXFsjdfwJj364WBLd8F2cwKtdpjRbsIM1KkJb08Ae2w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CO1PR11MB4947 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org hi, Paul, On Mon, Dec 11, 2023 at 08:26:12PM -0800, Paul E. McKenney wrote: > On Tue, Dec 12, 2023 at 10:06:36AM +0800, Oliver Sang wrote: > > hi, Paul, > > > > On Mon, Dec 11, 2023 at 08:59:16AM -0800, Paul E. McKenney wrote: > > > On Thu, Dec 07, 2023 at 04:19:56PM +0800, kernel test robot wrote: > > > > > > > > > > > > Hello, > > > > > > > > kernel test robot noticed "WARNING:at_kernel/rcu/tree_stall.h:#rcu_stall_chain_notifier_register" on: > > > > > > > > commit: 1254a620b4a3832e65ac01bcef769b99e34515b2 ("EXP locktorture: Add RCU CPU stall-warning notifier stub") > > > > https://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.git dev.2023.11.08a > > > > > > Thank you for your testing efforts! > > > > > > This one is expected behavior by explicit request from Linus Torvalds. > > > The concern is that people might use this hook without understanding > > > the risks of losing RCU CPU stall warnings. > > > > > > One fix would be to never specify the rcupdate.rcu_cpu_stall_notifiers > > > kernel boot parameter. Another would be to forgive this warning when > > > that boot parameter was specified. Your choice! ;-) > > > > Thanks a lot for information! > > > > this commit (1254a620b4) is a test for this warning, am I right? > > when this warning mechanism goes into upstream, do you want us still report > > for similar cases? or we could just ignore them? Thanks! > > This 1254a620b4 ("EXP locktorture: Add RCU CPU stall-warning notifier > stub") commit is a debug-only use of this facility that will never go > upstream, as signified by the "EXP" at the beginning of the subject line. > > Or is there some better way than "EXP" to mark commits that are not > intended for mainline? > > Thanx, Paul > sorry, seems I didn't state it very well. let me clarify. the 'EXP' and "This not-for-mainline commit" is very good for us to know it will not go into mainline. what I asked is if this warning is triggered by other usages (not this debug-only test), could we still ignore them by following below guidance you gave us? > > > One fix would be to never specify the rcupdate.rcu_cpu_stall_notifiers > > > kernel boot parameter. Another would be to forgive this warning when > > > that boot parameter was specified. Your choice! ;-)