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McKenney" , Metin Kaya , Xuewen Yan , Thomas Gleixner , "Daniel Lezcano" , Suleiman Souhlal , kuyo chang , hupu , References: <20260404053632.1729280-1-jstultz@google.com> <20260404053632.1729280-3-jstultz@google.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20260404053632.1729280-3-jstultz@google.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Received-SPF: None (SATLEXMB03.amd.com: kprateek.nayak@amd.com does not designate permitted sender hosts) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF00020E60:EE_|SA1PR12MB8118:EE_ X-MS-Office365-Filtering-Correlation-Id: 87a5c012-758c-41f4-f25b-08de920f2296 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|36860700016|82310400026|376014|1800799024|22082099003|56012099003|18002099003; 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)(7416014)(36860700016)(82310400026)(376014)(1800799024)(22082099003)(56012099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: p5nSfQX5knQ9Diyv/0XU7+xaX8bGzzfJDtXpkygGZLYbvB6GWcfGQu4T7oEvheBcNdTaweWw6ox92tHH/KBJw0/W3kTtJplX9cIGDL+S4pteqBXRwVWiGpcjt8ZssmwZLgOwVWyYaF4oXAEqwtHk/5B1ivZoVZWVeyqSqcSgPXPCU3xp3PqfLpwFka7ad5Hh8kppzOjiXZOzMwjZjUXQde3joL1iL5iMZJrgQ2Wct+njK7/RmyGlNmb/0O+kSZ/4ahZXnijilIpwfGM1wUNVTedZiC4pOlEyzMUnJ/BnRr0keHIzbZZgI1ahBmWuUElPwfxXW9/e4PBqve/9scBLZHXU8xanpEWGj63uuraZCp4R8VSyRL5TekLPiaG81woWT5UnDhvfJ3N1AHZW7llrAX/QLgleLHKtnp/f6JgwwhUb7nNfC41yCnrk1mDeBgDc X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Apr 2026 05:58:03.5387 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 87a5c012-758c-41f4-f25b-08de920f2296 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: BL6PEPF00020E60.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB8118 Hello John, On 4/4/2026 11:06 AM, John Stultz wrote: > With proxy-exec once we do return migration from ttwu(), if a > task is proxying for a waiting donor, and the donor is woken up, > we switch the rq->donor to point to idle briefly until we can > re-enter __schedule(). > > However, if a task that was acting as a proxy calls into > yield() right after the donor is switched to idle, it may > trip a null pointer traversal, because the idle task doesn't > have a yield_task() pointer. After introduction of proxy_resched_idle(), we shouldn't have any case of running with rq->idle as donor with a different rq->curr. I think we can drop this fix now and squash the changes from Patch 7 into Patch 6 to even avoid any transient cases during bisection where this might be possible Thoughts? -- Thanks and Regards, Prateek