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McKenney" , Metin Kaya , Xuewen Yan , Thomas Gleixner , Daniel Lezcano , "Suleiman Souhlal" , kuyo chang , hupu , , Mike Galbraith References: <20260526111609.433880331@infradead.org> <20260526113322.120970670@infradead.org> <20260529084712.GL343181@noisy.programming.kicks-ass.net> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20260529084712.GL343181@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA2PEPF000015CC:EE_|PH7PR12MB7259:EE_ X-MS-Office365-Filtering-Correlation-Id: 941cd67d-2cd1-4241-b871-08debd6f8d64 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|82310400026|36860700016|22082099003|18002099003|11063799006|4143699003|56012099006; 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:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(1800799024)(7416014)(376014)(82310400026)(36860700016)(22082099003)(18002099003)(11063799006)(4143699003)(56012099006);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 7hcIekxJKWN8IsD6rpTw3ztR4+Gv7B8vpyxoWqqjpc5ZLsi300ugiZohciEpoa0jMbhtuaXGtl3PebHHNiGicTBWvKSf4F5aShcZA9eP1Nlu+xrrZgzole+4ptB+H6BNVl5ta6ZnxjSHfv1ibbKYKIqn3zRprkCz2glIeS4JGCnClem0Qtzk4XJGYwIVNtIKla4YH5dDq+3h0AXWsK2/syJDoVGMFId9G+xkQX7LYCtcyHvz5xI+aDtXP3L0GIlIfZWP5JRGTQ4e2I0DfoEX60g4UZQJ5KIpjZzI5a8lCtNUTdtCOUNn83EijKBeR7Ra7NT75/RlF2yB9pJyQe8fm8Lw+SpRVUM5UcESLXhB+qHaMERjtzQY4Tr7mQmEucn4KTNHcqa8hP/gPOfjHDtrSbsBX5sIjGNOVSGwc/Ny+LlQza9zg+Fi/EbQXO1W1gOA X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 May 2026 10:46:34.3668 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 941cd67d-2cd1-4241-b871-08debd6f8d64 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: SA2PEPF000015CC.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB7259 Hello Peter, On 5/29/2026 2:17 PM, Peter Zijlstra wrote: > Egads, this is terrible. This means all is_blocked tasks always end up > taking blocked_lock. > > The other suggestion (in the other subthread) was to simply delay this > patch until the end. That seems far more sensible. > > Anyway, let me go try and find your git tree and see what you ended up> with. Now that I look at this again, yeah, you can simply move that optimization later too. Github isn't letting me push the branch but essentially you move: e2ff8b7bde07 sched/proxy: Only return migrate when needed 1b89b7b21bf5 sched/proxy: Remove superfluous clear_task_blocked_in() to happen after commit a8be1edac5a1 ("sched/proxy: Remove PROXY_WAKING"). All of that was for essentially this scenario: mutex_lock() set_task_blocked_on(mutex) schedule_preempt_disabled() __schedule() p->is_blocked = 1 -------> preempted __send_signal_locked() signal_wake_up() try_to_wake_up() ttwu_runnable() /* * Needs to clear p->blocked_on * As long as PROXY_WAKING exists. */ ttwu_do_wakeup() p->__state = TASK_RUNNING p->is_blocked = 0 mutex_unlock() set_task_blocked_on_waking(p, mutex) p->blocked_on = PROXY_WAKING; /* p->is_blocked = 0; p->blocked_on = PROXY_WAKING */ next = p; <------ swich_in /* Exits out of schedule_preempt_disabled() */ set_task_blocked_on(p, mutex) !!! p->blocked_on == PROXY_WAKING !!! -- Thanks and Regards, Prateek