From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 164BEC28D13 for ; Mon, 22 Aug 2022 07:43:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231382AbiHVHnZ (ORCPT ); Mon, 22 Aug 2022 03:43:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60806 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232786AbiHVHnX (ORCPT ); Mon, 22 Aug 2022 03:43:23 -0400 Received: from NAM12-MW2-obe.outbound.protection.outlook.com (mail-mw2nam12on2049.outbound.protection.outlook.com [40.107.244.49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EAB42703; Mon, 22 Aug 2022 00:43:22 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=GGQouZ0TXJF2FGmlxiFtmlE+GKA5lZjZQzz1vOtOwkipmKkXYBrbpeITQwJulv9EzP3dhpLWUKN7xWNnzLWBRaR6oV1LSw1i6/5UqFRmunnCubjFxM2ud1PeMSbVsbUG+/GzVK1NwUxwzPAORmE55EOHlFjcfpZsHW5Iz9fL8TJvple/EEWwEHOfTF2ZwyAE+k5NNjmVZv4pVx/Xco9VdE2g1wefOpQYWX+Ylt65PB1z289zMyws5745KBXXRmUZ1EFplcfj1fWeGvE7PkrPm1gpOQNxcxTQUVv5FQbosR1Lc1zr8jibpm6+DN/BsV3BdVWS9DrDOshGKwJNrv8I7Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=5KWU5v2Lp3zUFZUWGFyqJXPrcmikXVcANqtkgtN5ACQ=; b=V2D/LDar7tcTv0w1hbs2jF99lsXVkvhLiyIWVlEKSTAtX5gpzESeAlKPJUmsAdjS1BzZHznbM+wJ6oP+7+J9wBvRfk88+dzRRTPK5jezKb2biZ+B1p9S/kVEUg2xBPFdW9AfQvGIqws4aYFGWjt4J/B8vMag7pELBrs9XSAT46tN2njCUuQyrGP1ne5Gk1zGoxj90QnfpKns84XFIREAZUAWZ60sI/3+HFch78vEujRlFAa3VuGa6AApcIeJK9nZG2PXnlIcpgEklMrWDZaG4/fsb4rt0JWBwRBQscltsd/m4cgBGsJOrNbvXaQ4PTm+oh8EF+LRV83T0Guittuw4w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=vmware.com; dmarc=pass action=none header.from=vmware.com; dkim=pass header.d=vmware.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=vmware.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=5KWU5v2Lp3zUFZUWGFyqJXPrcmikXVcANqtkgtN5ACQ=; b=z3AU6RMNwwJNmh6z/g7ZzwZZjF/jzSDGthKoiC6tRdOyvl71VW8arF+EEDx66gUAX99MwbtlWlQX3V1DPkk22U/jmyr9JnCdl0iFFed9qF6OyUOSnsJ3TLexHO1zH7xz7ivhgm4r6Glu7w02q/Sx5Px+ahG/EaDWx+DzwYK3A4Q= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=vmware.com; Received: from SA1PR05MB8311.namprd05.prod.outlook.com (2603:10b6:806:1e2::19) by DM4PR05MB9253.namprd05.prod.outlook.com (2603:10b6:8:8c::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5566.8; Mon, 22 Aug 2022 07:43:20 +0000 Received: from SA1PR05MB8311.namprd05.prod.outlook.com ([fe80::c0a2:3165:1ca9:254d]) by SA1PR05MB8311.namprd05.prod.outlook.com ([fe80::c0a2:3165:1ca9:254d%7]) with mapi id 15.20.5566.014; Mon, 22 Aug 2022 07:43:20 +0000 From: Ankit Jain To: juri.lelli@redhat.com, bristot@redhat.com, l.stach@pengutronix.de, suhui_kernel@163.com, msimmons@redhat.com, peterz@infradead.org, glenn@aurora.tech, stable@vger.kernel.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org Cc: srivatsab@vmware.com, srivatsa@csail.mit.edu, akaher@vmware.com, amakhalov@vmware.com, vsirnapalli@vmware.com, sturlapati@vmware.com, bordoloih@vmware.com, keerthanak@vmware.com, Ankit Jain Subject: [PATCH v5.4.y 1/4] sched/deadline: Unthrottle PI boosted threads while enqueuing Date: Mon, 22 Aug 2022 13:09:39 +0530 Message-Id: <20220822073942.218045-2-ankitja@vmware.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220822073942.218045-1-ankitja@vmware.com> References: <20220822073942.218045-1-ankitja@vmware.com> Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: SJ0PR13CA0183.namprd13.prod.outlook.com (2603:10b6:a03:2c3::8) To SA1PR05MB8311.namprd05.prod.outlook.com (2603:10b6:806:1e2::19) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: ac87bbab-032c-4c51-2d94-08da8411fc28 X-MS-TrafficTypeDiagnostic: DM4PR05MB9253:EE_ X-LD-Processed: b39138ca-3cee-4b4a-a4d6-cd83d9dd62f0,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SA1PR05MB8311.namprd05.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230016)(4636009)(136003)(366004)(39860400002)(346002)(396003)(376002)(86362001)(6666004)(83380400001)(36756003)(38350700002)(38100700002)(2616005)(52116002)(6506007)(26005)(921005)(186003)(1076003)(6512007)(478600001)(6486002)(107886003)(966005)(2906002)(4326008)(41300700001)(66946007)(5660300002)(7416002)(66556008)(8676002)(8936002)(66476007)(316002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?2sCAkcZb2knxTSv2fgrCfstdYTgBYU1SwZpSn8sJzHKZvhzdMtw6X1Dj6jcE?= =?us-ascii?Q?pvm/OxXal/3e1E0SX1RaPKSNHvvwZ53nHJiMukhJbe9M5gLpuQNpQ2u6ngAC?= =?us-ascii?Q?s5es4/Or1izfyEcMnpOvIHOBHWtTrOlyFDHRnRNj5ST129irIzEjoZvofmYd?= =?us-ascii?Q?Xy4S2uqw1cKlRPysTyEXeWnrmh1r/Zd3XAlE2oumpPP7HYAr7RcNN98oaJlJ?= =?us-ascii?Q?0GQ5ermJ3d9nWSRqpXbeTAn+oNcs20hPm4Rl24OmiOkYKUumCjZABOVguYdW?= =?us-ascii?Q?+fAZCbsAHFbUJcia50lwRUo2IbYvsI1rFDDnP7Wbq0pz8qclGiiStOo1ko8s?= =?us-ascii?Q?qKktl0ftBrce1fx5Kgs0ziQfPUwn4oK4Nk26SkPaplxY0vQVRojyluESnG62?= =?us-ascii?Q?5/dgXKvYho3UK1eGUQDLSWwETO4aeTDS7+8I0NeE5BOAMwS4/c9A+MZXMA8X?= =?us-ascii?Q?3407+6FioC+QiaRYlZlXRJTWY9U1ZWsJ5cb9AAWtGooOR0he7r7RVLD6n+Us?= =?us-ascii?Q?mZU6uPtL3uM92iDhqLnMVj2Dllg06c5SvMlCgm1lx/6W+hv5QW4otJdMrwF/?= =?us-ascii?Q?nibrznZxuhkyZJ3cILVBi2+K9kUsmLzKWKXYS66UsfLqovhahjWMyE4Zioe/?= =?us-ascii?Q?3eJpSYvXAN6Kd6OtRLCxaXpBDnK17dFXAmaQ0BsvDkW/pgzwNPj9b//HcGGE?= =?us-ascii?Q?K/3Uvrv6I/iSX/J7JEmYYyKpw/7em6vceJuO4cgaKxoaeHFIAvB1W5kJBBuj?= =?us-ascii?Q?FuN83SAwB/kV4DMP8KWpWm2sXNOBz/t3NGJGVMXK+5kUjQVk8obnvshzOqG+?= =?us-ascii?Q?gC1bW2MKhqXeradKRSwstXgsOOQ/Pp0+62lT6w65ktisXHv80QfOFOS2sNUY?= =?us-ascii?Q?pC57eW1kTduwkDA32SUXOnVOUip8yji9/WBkutcyqklYFf7L1n0ZPSim2yql?= =?us-ascii?Q?J1obM3rCuihbYAe+hvKINuWOdx3SMrN3+miHva4jjWLEtCtm+4lRHQMgOIDz?= =?us-ascii?Q?ocpTDugpwxOII7oO5Y8muyTQ00T0ki32jy7nSswYyQsqRbK1cddV+n54+JWG?= =?us-ascii?Q?qW0IPh0C2Eaq9Q5uS2jM3zpd4CaIIh3rI6qahO8R/OKzIm/Fg6gSFLiy3yc6?= =?us-ascii?Q?yfWfnqMUHxsVcDnsTMMrFhIC3WzvoF3K/gRWWh9tlpZSQKkqtuJJQGI0onvP?= =?us-ascii?Q?cmC8TvnszcTr9VgjFWi+w2ZXgepOjt8502sGpN6UKxHw/RUhbSGwc4DsBn2r?= =?us-ascii?Q?ion8PgRRW9lRk5H0XStewKyjw8mfg0lCMNumPYmGNIhpLJNvyq8hzMvB0zWk?= =?us-ascii?Q?f9O2fSRXNG8Yxn2EErVmlvhw7PMVp/hWbetiJk217Z/vgxpVt8B5GrswE7gX?= =?us-ascii?Q?gLqyqvTXkNfCEWK+Nhwjm+gclIljeM4c2R15qrabSaim4wfDH4hhPadx4wFW?= =?us-ascii?Q?GyDT+0spEeuWAhv69+/JATHapmTG6sqOqU/DJ6XhloHn83/DH8OOhIkQcoqO?= =?us-ascii?Q?kYeOb47+bJ4X+vHR/Lnb8UfrIEIOhP0+CmcN6mglzxOja+Tcj4u1uGI1j+uK?= =?us-ascii?Q?/pGqchmi4vN3qMujmUGIjFiUf3+uCq+q1Ykb/cQm?= X-OriginatorOrg: vmware.com X-MS-Exchange-CrossTenant-Network-Message-Id: ac87bbab-032c-4c51-2d94-08da8411fc28 X-MS-Exchange-CrossTenant-AuthSource: SA1PR05MB8311.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Aug 2022 07:43:20.8179 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: b39138ca-3cee-4b4a-a4d6-cd83d9dd62f0 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: ptDISjaMIBIpsGwowbQRVCN9s7mXQgrX23juq+xk7+YzwzPuoYHpsgaqwpjEkR+7Ueqb5u0dbUy2gnqRmogSOg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR05MB9253 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Daniel Bristot de Oliveira commit feff2e65efd8d84cf831668e182b2ce73c604bbb upstream. stress-ng has a test (stress-ng --cyclic) that creates a set of threads under SCHED_DEADLINE with the following parameters: dl_runtime = 10000 (10 us) dl_deadline = 100000 (100 us) dl_period = 100000 (100 us) These parameters are very aggressive. When using a system without HRTICK set, these threads can easily execute longer than the dl_runtime because the throttling happens with 1/HZ resolution. During the main part of the test, the system works just fine because the workload does not try to run over the 10 us. The problem happens at the end of the test, on the exit() path. During exit(), the threads need to do some cleanups that require real-time mutex locks, mainly those related to memory management, resulting in this scenario: Note: locks are rt_mutexes... ------------------------------------------------------------------------ TASK A: TASK B: TASK C: activation activation activation lock(a): OK! lock(b): OK! lock(a) -> block (task A owns it) -> self notice/set throttled +--< -> arm replenished timer | switch-out | lock(b) | -> B prio> | -> boost TASK B | unlock(a) switch-out | -> handle lock a to B | -> wakeup(B) | -> B is throttled: | -> do not enqueue | switch-out | | +---------------------> replenishment timer -> TASK B is boosted: -> do not enqueue ------------------------------------------------------------------------ BOOM: TASK B is runnable but !enqueued, holding TASK C: the system crashes with hung task C. This problem is avoided by removing the throttle state from the boosted thread while boosting it (by TASK A in the example above), allowing it to be queued and run boosted. The next replenishment will take care of the runtime overrun, pushing the deadline further away. See the "while (dl_se->runtime <= 0)" on replenish_dl_entity() for more information. Reported-by: Mark Simmons Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Juri Lelli Tested-by: Mark Simmons Link: https://lkml.kernel.org/r/5076e003450835ec74e6fa5917d02c4fa41687e6.1600170294.git.bristot@redhat.com [Ankit: Regenerated the patch for v5.4.y] Signed-off-by: Ankit Jain --- kernel/sched/deadline.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 2bda9fdba31c..fdeb2afffc48 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1484,6 +1484,27 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) */ if (pi_task && dl_prio(pi_task->normal_prio) && p->dl.dl_boosted) { pi_se = &pi_task->dl; + /* + * Because of delays in the detection of the overrun of a + * thread's runtime, it might be the case that a thread + * goes to sleep in a rt mutex with negative runtime. As + * a consequence, the thread will be throttled. + * + * While waiting for the mutex, this thread can also be + * boosted via PI, resulting in a thread that is throttled + * and boosted at the same time. + * + * In this case, the boost overrides the throttle. + */ + if (p->dl.dl_throttled) { + /* + * The replenish timer needs to be canceled. No + * problem if it fires concurrently: boosted threads + * are ignored in dl_task_timer(). + */ + hrtimer_try_to_cancel(&p->dl.dl_timer); + p->dl.dl_throttled = 0; + } } else if (!dl_prio(p->normal_prio)) { /* * Special case in which we have a !SCHED_DEADLINE task -- 2.34.1