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client-ip=165.204.84.17; helo=satlexmb08.amd.com; pr=C Received: from satlexmb08.amd.com (165.204.84.17) by SJ1PEPF00001CEB.mail.protection.outlook.com (10.167.242.27) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.451.8 via Frontend Transport; Thu, 24 Sep 2026 08:10:34 +0000 Received: from satlexmb08.amd.com (10.181.42.217) 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 15.2.2562.49; Thu, 24 Sep 2026 03:10:33 -0500 Received: from [10.136.33.35] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.49 via Frontend Transport; Thu, 24 Sep 2026 03:10:28 -0500 Message-ID: <05319013-86e6-4a80-bb8f-385657cee410@amd.com> Date: Thu, 24 Sep 2026 13:40:27 +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: [PATCHSET v14 sched_ext/for-7.4] sched: Make proxy execution compatible with sched_ext To: Peter Zijlstra , Andrea Righi CC: Tejun Heo , David Vernet , Changwoo Min , John Stultz , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Christian Loehle , David Dai , Koba Ko , Aiqun Yu , Shuah Khan , , References: <20260922165445.943315-1-arighi@nvidia.com> <20260924075237.GH2009045@noisy.programming.kicks-ass.net> <20260924075925.GE4121620@noisy.programming.kicks-ass.net> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20260924075925.GE4121620@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: 7jEplqX1jtWfUF7XvqjHcqze436Q8WePF1YofTPKDoxmFE3iZe5qQpi+7ZyqqstnQPZUNzIFnf28sx8IlEYJLWrZPngiRWI8XeqAaHdr9Zyw0oakoBQvwNOngO9dMp6Nio5vo0aGJcCwBZYDsawQFHaslVZ+QME4lgSjZFzIKP2Et68pVUz73N0kCw0guk1OFhnu4x0oDWRqANaup8Mbu8P9KSwxXqYNytsv+6fJqEAS7Lqep68Yc+v0Ftku5jDooDx55h7R1xc083rDHDlJ854gR3z7zt9qPoBU33RQCyqn9Ch8hrd73vXgPNskfejL40Mvcrf37Lq+OlroBMQ6xnnfDdLbbSC1e1nIdR4j/rvs0W9od0gbo2+C0N4BwmwhvndsF321ivF5bvCPVYTT7avzvtRpmM3vhKYN+p0GGnGj+1n8ZKi3bP9Sc1JUs+Wg X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Sep 2026 08:10:34.2655 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: ea3a9070-6c62-4fee-a56c-08df1a134f18 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: SJ1PEPF00001CEB.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB8796 On 9/24/2026 1:29 PM, Peter Zijlstra wrote: >> Almost like switching_to_scx(), except it needs to change ctx->queued in case >> of p->is_blocked. Hence a new callback ran before sched_change_begin(). > > And I wonder, would something like so work? > > --- > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index adcc9264c0c6..3e7691d24930 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -11215,8 +11215,13 @@ void sched_change_end(struct sched_change_ctx *ctx) > */ > WARN_ON_ONCE(p->sched_class != ctx->class && !(ctx->flags & ENQUEUE_CLASS)); > > - if ((ctx->flags & ENQUEUE_CLASS) && p->sched_class->switching_to) > - p->sched_class->switching_to(rq, p); > + if ((ctx->flags & ENQUEUE_CLASS) && p->sched_class->switching_to) { > + bool block = p->sched_class->switching_to(rq, p); > + if (block && p->is_blocked) { Shouldn't this also check for "ctx->queued"? > + block_task(rq, p, READ_ONCE(p->__state)); Otherwise we may block an already off rq task. > + ctx->queued = false; > + } > + } > > if (ctx->queued) > enqueue_task(rq, p, ctx->flags); -- Thanks and Regards, Prateek