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client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by CH3PEPF00000017.mail.protection.outlook.com (10.167.244.122) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9791.0 via Frontend Transport; Mon, 30 Mar 2026 14:37:16 +0000 Received: from Satlexmb09.amd.com (10.181.42.218) 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 15.2.2562.17; Mon, 30 Mar 2026 09:37:15 -0500 Received: from satlexmb08.amd.com (10.181.42.217) by satlexmb09.amd.com (10.181.42.218) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Mon, 30 Mar 2026 07:37:15 -0700 Received: from [172.31.184.125] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Mon, 30 Mar 2026 09:37:11 -0500 Message-ID: <73dab51a-650f-4c82-9e73-13236b2a26c2@amd.com> Date: Mon, 30 Mar 2026 20:07:06 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/7] sched/fair: Fix zero_vruntime tracking To: Peter Zijlstra , John Stultz CC: , , , , , , , , , , , , , Suleiman Souhlal References: <20260219075840.162631716@infradead.org> <20260219080624.438854780@infradead.org> <20260330101018.GN3738786@noisy.programming.kicks-ass.net> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20260330101018.GN3738786@noisy.programming.kicks-ass.net> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: DejJDAQEM4y4bbYHn77UXW//hpF6gO3yo2AMJnt0LGZJ8KeWjFepmrx/XexbaZbU7l5YAylRrNHjaxjK2KyytCppvsbuRLTbRhckpPhLuSocNZwpwpm/eN9pL1jxQ809jC+QnWG5mpDIVmv97nHEmtlE7zrFiu6ysRmC/WRBB+mxfWHj2fjuYshfuxOH+0jfAUCUhlBafkbfG9NyzCOjq0jbm3nwF8RKI1l2IUv4nU8Fm3vo4kLG9nU47Q+uiZyngmmfaPFWGdqv66aNioqZu9PNwyXUSsdkS5ANoBWkm+Fgcatr3h34VPw4Wfz2aqfzp6FbtJAYpO/B7riNdmYq/XwjoVubJzAFbT1K0C/Ptv6Q6oLIOcV1yip6xadzbvR33D/z+kapYrn8sj3hb8ON+BON1dEZ00HSqou5cmTMA+xTuzptiEvhYxXoCztfNILh X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Mar 2026 14:37:16.1565 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 5964e99a-6628-48bb-de09-08de8e69d6f4 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: CH3PEPF00000017.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4057 Hello Peter, On 3/30/2026 3:40 PM, Peter Zijlstra wrote: > This means, that if the two tasks playing leapfrog can reach the > critical speed to reach the overflow point inside one tick's worth of > time, we're up a creek. > > If this is indeed the case, then the below should cure things. I have been running with this for four hours now and haven't seen any splats or crashes on my setup. I could reliably trigger the warning from __sum_w_vruntime_add() within an hour previously so it is safe to say I was hitting exactly this. Feel free to include: Tested-by: K Prateek Nayak -- Thanks and Regards, Prateek