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Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by LV8PEPF0000005B.mail.protection.outlook.com (10.167.245.136) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.472.14 via Frontend Transport; Thu, 1 Oct 2026 19:33:50 +0000 Received: from BLRKPRNAYAK.amd.com (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.49; Thu, 1 Oct 2026 14:33:42 -0500 From: K Prateek Nayak To: Peter Zijlstra , Chen Yu , "Tim Chen" , Ingo Molnar , Juri Lelli , Vincent Guittot , "Andrew Morton" , Arnd Bergmann , , , , , , , CC: Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Shrikanth Hegde , K Prateek Nayak Subject: [RFC PATCH v3 12/13] sched/fair: Allocate nohz.idle_cpus_mask during sched_init_smp() Date: Thu, 1 Oct 2026 19:28:48 +0000 Message-ID: <20261001192849.74788-13-kprateek.nayak@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261001192849.74788-1-kprateek.nayak@amd.com> References: <20261001192849.74788-1-kprateek.nayak@amd.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 Content-Type: text/plain X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LV8PEPF0000005B:EE_|PH8PR12MB6914:EE_ X-MS-Office365-Filtering-Correlation-Id: 8589f937-980e-4b95-4b12-08df1ff2eb95 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|23010399003|7416014|82310400026|36860700016|1800799024|921020|56012099006|11063799006|10067099003|22082099003|18002099003|6133799003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: x/U7m3hZ+Ybv/VT5cWof8MeqztyT/sBoiy55dKgQ/wv4u4uNNXR/bZ4+1yklcsyaAeKCEhz2TQIyiQ0QTdrnrKu2M4zfFkrvSpyLDMThe3sJGPlNlakfteBpSN853nFh4QFf7J2ecciLnCisvbS8UCSAvIEBFZ3mVsQxo5MxBHaIih3pKE46cMMx54uzFMmHGIf0IbtYrtyTFFWd/0EPkskSYQuzHkaIgrkxa+pA7jh4d0IrIEI6URXg36+KQ5L9H0h+A7paPWs9nMNofJ7zKHY5becCEpCL4tFv4+MHdFJICx3+EnQfFZTfmRLSAtLjOZqotoavXQ9S3ToJh85+psIiKFf28Tq3QVUHlUnaylTUYas+cYVNHmq1L7JcI2NRe3768P73eEGlKBojarQhBlHj8LZK+tlri8yV/GxBxtTlJccfIEJwUcF0umDQ6bXe X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Oct 2026 19:33:50.4432 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 8589f937-980e-4b95-4b12-08df1ff2eb95 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: LV8PEPF0000005B.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR12MB6914 nohz.idle_cpus_mask is not required soon after early initialization since the boot CPU cannot go tickless idle before CPU is activated and tick is started. Defer allocation of nohz.idle_cpus_mask to sched_init_smp() via init_sched_fair_class_smp(). This is preparation to convert nohz.idle_cpus_mask to sparsebitmap (sbm) which requires architectures to finish smp_prepare before initializing the core bits. No functional changes intended. Signed-off-by: K Prateek Nayak --- kernel/sched/core.c | 2 ++ kernel/sched/fair.c | 8 +++++++- kernel/sched/sched.h | 1 + 3 files changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 977f579da410..127aed81d316 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8849,6 +8849,8 @@ int sched_cpu_dying(unsigned int cpu) void __init sched_init_smp(void) { + init_sched_fair_class_smp(); + sched_init_numa(NUMA_NO_NODE); prandom_init_once(&sched_rnd_state); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 1c687c3c70f1..a0a659f4c3be 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -15645,6 +15645,13 @@ void show_numa_stats(struct task_struct *p, struct seq_file *m) } #endif /* CONFIG_NUMA_BALANCING */ +__init void init_sched_fair_class_smp(void) +{ +#ifdef CONFIG_NO_HZ_COMMON + zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); +#endif +} + __init void init_sched_fair_class(void) { int i; @@ -15666,6 +15673,5 @@ __init void init_sched_fair_class(void) #ifdef CONFIG_NO_HZ_COMMON nohz.next_balance = jiffies; nohz.next_blocked = jiffies; - zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); #endif } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 7d2ec527b8a2..0726e8fb5967 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -3024,6 +3024,7 @@ extern void update_max_interval(void); extern void init_sched_dl_class(void); extern void init_sched_rt_class(void); extern void init_sched_fair_class(void); +extern void init_sched_fair_class_smp(void); extern void resched_curr(struct rq *rq); extern void resched_curr_lazy(struct rq *rq); -- 2.34.1