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Fri, 10 Jul 2026 23:48:11 +0000 Message-ID: Date: Fri, 10 Jul 2026 16:48:09 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 08/10] fs/resctrl: Do not invoke smp_processor_id() in preemptible context To: Chen Yu , CC: , , , , , , , , , , , Hongyu Ning References: From: Reinette Chatre Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MW4PR04CA0145.namprd04.prod.outlook.com (2603:10b6:303:84::30) To SJ2PR11MB8370.namprd11.prod.outlook.com (2603:10b6:a03:540::20) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ2PR11MB8370:EE_|CH2PR11MB8833:EE_ X-MS-Office365-Filtering-Correlation-Id: fe969415-f514-495e-cb83-08dededdb3aa X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|7416014|376014|1800799024|23010399003|18002099003|22082099003|11063799006|56012099006|4143699003|5023799004|6133799003; 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The MMIO-based CMT will set any_cpu to true in a > follow-up patch. This change will trigger a warning when calling Please drop the "in a follow-up patch" since that becomes irrelevant after merge. Also please rewrite this paragraph to not just describe code but what this actually means at a high level. > smp_processor_id() inside __l3_mon_event_count(), because > __l3_mon_event_count() may be invoked from arbitrary CPUs in task > context. Since the calling context is preemptible here, > smp_processor_id() will emit a debug warning. > > To prepare for MMIO-based CMT reads, skip the current CPU lookup > when an event's any_cpu flag is set. Events with this flag do not > require execution on a specific CPU. Please note there is an upcoming change that will impact this change. Nothing major, the change should be clear. https://lore.kernel.org/lkml/6b3c66a49788828bd8c04a6911bd74c91ccd56f3.1782857711.git.reinette.chatre@intel.com/ Reinette