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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=satlexmb08.amd.com; pr=C Received: from satlexmb08.amd.com (165.204.84.17) by BN6PEPF00000073.mail.protection.outlook.com (10.167.248.200) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.569.4 via Frontend Transport; Mon, 26 Oct 2026 03:10:00 +0000 Received: from satlexmb07.amd.com (10.181.42.216) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.53; Sun, 25 Oct 2026 22:09:54 -0500 Received: from [10.136.43.232] (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server id 15.2.2562.53 via Frontend Transport; Sun, 25 Oct 2026 22:09:48 -0500 Message-ID: <637331bf-1b4c-4c1c-8205-0636c93d990a@amd.com> Date: Mon, 26 Oct 2026 08:39:47 +0530 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v33 4/7] sched/proxy: Set TASK_RUNNING when shortcuting return migration To: Andrea Righi , John Stultz CC: LKML , Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Juri Lelli , Vincent Guittot , Valentin Schneider , Suleiman Souhlal , Metin Kaya , Dietmar Eggemann , Steven Rostedt , Zimuzo Ezeozue , Waiman Long , Boqun Feng , "Paul E. McKenney" , Joel Fernandes , Qais Yousef , Xuewen Yan , kuyo chang , hupu , Zhan Xusheng , "zhidao su (Xiaomi)" , Hui Su , "Shubhang Kaushik (Ampere)" , References: <20261023220431.1106611-1-jstultz@google.com> <20261023220431.1106611-5-jstultz@google.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN6PEPF00000073:EE_|CH3PR12MB7572:EE_ X-MS-Office365-Filtering-Correlation-Id: cff4954e-562a-4d03-3d60-08df330e9f09 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|23010399003|1800799024|82310400026|36860700016|261022105027099003|261022075727099003|261021135927099003|10067099003|56012099006|18002099003|22082099003|11063799006|4143699003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb08.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(7416014)(376014)(23010399003)(1800799024)(82310400026)(36860700016)(261022105027099003)(261022075727099003)(261021135927099003)(10067099003)(56012099006)(18002099003)(22082099003)(11063799006)(4143699003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: bjHNUjp6TRgvHO1j/54JKJyVsmICDjCEySgbst27reE3hFuJJ/jSzAbaakLQggyr32rD5tW7tbg/KUy7oPn4ikPw3sivbWJBRAHryOsi4kRVTt6kRPU74eFBs7DLVMJRljfsIkfgQbIY0q7DiaDaQoJqYVxGi9lz7p+vp8SS1oXFaGs0zZA9O36H6pA3HyNnyjVO0tajbD1mvhehwf3+BriRn/AfbWf/lPPG+7YeX09aQe5Mp2w5xXX5GOLuvr+prPF8HiGPKXXuX0FKzx7jnnUA4wmA63bPfQWFII70ZDim4AC18bSvTIINf27Vhl/I+/xB7hHA8mxbOF40fwpMvXdduySOq6biF4XvCFsu/ZZpvC2MUuBeNUOW3bkRAfruA6O7cvGtni4X1VRLJzBICrPMFYRVneX7GgeSDHXHAZ9/mQiyqI1q84sLpfAB6tS3 X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Oct 2026 03:10:00.0195 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: cff4954e-562a-4d03-3d60-08df330e9f09 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=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN6PEPF00000073.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB7572 Hello Andrea, On 10/24/2026 2:06 PM, Andrea Righi wrote: >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index 2cb42de255f7a..43ba76b5a3464 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -7028,6 +7028,7 @@ find_proxy_task(struct rq *rq, struct task_struct *donor, struct rq_flags *rf) >> clear_task_blocked_on(p, mutex); >> if (task_current(rq, p) || p->wake_cpu == task_cpu(p)) { >> p->is_blocked = 0; >> + WRITE_ONCE(p->__state, TASK_RUNNING); >> return p; >> } >> goto activate; > > This is basically an inlined ttwu_do_wakeup() without > trace_sched_wakeup(). > >> @@ -7065,6 +7066,7 @@ find_proxy_task(struct rq *rq, struct task_struct *donor, struct rq_flags *rf) >> __clear_task_blocked_on(p, NULL); >> if (task_current(rq, p) || p->wake_cpu == task_cpu(p)) { >> p->is_blocked = 0; >> + WRITE_ONCE(p->__state, TASK_RUNNING); >> return p; >> } >> goto activate; > > Ditto. > > Can we just call ttwu_do_wakeup(p)? It'd also avoid having two copies of > the same state transition that can diverge. That is a good idea but I wonder issuing a sched_wakeup trace without a corresponding sched_waking trace will trip some tracing scripts. That said having a __ttwu_do_wakeup() to consolidate all the task state changes in indeed a good idea. It should technically look like a __schedule() raced with a wakeup. Thoughts? -- Thanks and Regards, Prateek