From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1352585-1520124538-2-17028076930258483289 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.249, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='com', MailFrom='org', XOriginatingCountry='US' X-Spam-charsets: plain='iso-8859-1' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1520124537; b=B1Aqc8RdvQI94c7n9a2BxWMguX8CTy9BXwaKcpACXWqi73W YFF/FmmZIA86wkxBihCgh1erlxkBjx76E5O3c1Px8GFTDWszxzW2/PeY0ib54fOE vIMCZ0BaVaClx60q5vvxo+G0gTOZOTSJGr7Z0DnctGv0Zj3gR3NwSxQV41xcheE9 Sm0Ip9ZiDgMpCkM5EEcD867GluyzZcSUTtQMaXLOjePsWuQ9NrHuKpdx1zS+3dV1 DlBl5wWcgTkThz2BMDoYvtl0NOa5zl3lM+6CFhIOG8qbI0pQm8HqHmrhrMfGO7nW M1uVPvsT/dhe0qw+BdIABlHXgnN8XXZCJbl5nEw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :references:in-reply-to:content-type:content-transfer-encoding :mime-version:sender:list-id; s=arctest; t=1520124537; bh=QHeUk6 kxBjDOsD6z66CaX7utFsSaxCfWnD93EOs5RkA=; b=ZFvXFm1M4ZQC52BZujbHUQ o7aOMmAS2nl0Sy/Nx3/4mXK/1lU4eCYaR/k4Fqw/2VJ4e9xdC9pvevAE0qbVBZDe gvEB+vKloOI18rb+WhzCFb0ajOoeKL33997F63kXgxP2Ozdi5CHJDKp7I1z8HAG7 kE6h8ZmtkmuyZ85EY7NOKtKiovkWmzsuIMhtRI8bIs1psagGKtMG7quBRhf/fyhf YSgemniFvvVgvYauqMqjGIusx1igXLsUqkym49NQD8JhXr6OY3VAk1I+LGH5WMO8 Z1dc5oGomLade15Dj8g2GXnL0Sq+8i3kHCKcIggJWDrkvEOhAmusrhCQBbKQI7Ag == ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=pass (1024-bit rsa key sha256) header.d=microsoft.com header.i=@microsoft.com header.b=IkiRyxrg x-bits=1024 x-keytype=rsa x-algorithm=sha256 x-selector=selector1; dmarc=pass (p=reject,has-list-id=yes,d=none) header.from=microsoft.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=microsoft.com header.result=pass header_is_org_domain=yes Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=pass (1024-bit rsa key sha256) header.d=microsoft.com header.i=@microsoft.com header.b=IkiRyxrg x-bits=1024 x-keytype=rsa x-algorithm=sha256 x-selector=selector1; dmarc=pass (p=reject,has-list-id=yes,d=none) header.from=microsoft.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=microsoft.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932361AbeCDAsa (ORCPT ); Sat, 3 Mar 2018 19:48:30 -0500 Received: from mail-bn3nam01on0125.outbound.protection.outlook.com ([104.47.33.125]:5638 "EHLO NAM01-BN3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932322AbeCCWYr (ORCPT ); Sat, 3 Mar 2018 17:24:47 -0500 From: Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" CC: "Paul E. McKenney" , Ingo Molnar , Peter Zijlstra , Sasha Levin Subject: [PATCH AUTOSEL for 4.15 019/102] sched: Stop switched_to_rt() from sending IPIs to offline CPUs Thread-Topic: [PATCH AUTOSEL for 4.15 019/102] sched: Stop switched_to_rt() from sending IPIs to offline CPUs Thread-Index: AQHTsz5g8mEXITL+ckiGvD12w2a8pQ== Date: Sat, 3 Mar 2018 22:24:20 +0000 Message-ID: <20180303222318.26006-19-alexander.levin@microsoft.com> References: <20180303222318.26006-1-alexander.levin@microsoft.com> In-Reply-To: <20180303222318.26006-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;MW2PR2101MB0970;7:E2RDiWh7oOv8jifjrqSV7OslAph3vpDRTDwMk8uUa+NOnrFZds6rcjHTBwa0eNTpuOdEu6BiloO+Q97sKvwUzlgwJVkb595m8JAb3wZY6w5Ns6ZYPmqHm4NaV0pzHw/yqjqLvnw/iZOxUS8h1eh8JdzuQlLD7o7FLX+Etp/dse8xP8VyR5gf2V9vTf/1Qsn3t1RxKSWinkUssjuwAf0FIgyIpVoiQ0f5/c/1YJYyJsFyOQfqwMR/wEeqJ79tQroO x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: bf6f0139-b68f-4afd-db06-08d5815590ce x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(4534165)(4627221)(201703031133081)(201702281549075)(48565401081)(5600026)(4604075)(3008032)(2017052603307)(7193020);SRVR:MW2PR2101MB0970; x-ms-traffictypediagnostic: MW2PR2101MB0970: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Alexander.Levin@microsoft.com; x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(28532068793085)(89211679590171)(104084551191319); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(8211001083)(61425038)(6040501)(2401047)(5005006)(8121501046)(93006095)(93001095)(10201501046)(3002001)(3231220)(944501244)(52105095)(6055026)(61426038)(61427038)(6041288)(20161123562045)(20161123558120)(20161123560045)(20161123564045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(6072148)(201708071742011);SRVR:MW2PR2101MB0970;BCL:0;PCL:0;RULEID:;SRVR:MW2PR2101MB0970; x-forefront-prvs: 0600F93FE1 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(346002)(39860400002)(366004)(39380400002)(376002)(396003)(199004)(189003)(3660700001)(10290500003)(2950100002)(3846002)(2900100001)(22452003)(10090500001)(86612001)(6116002)(6666003)(68736007)(105586002)(5660300001)(5250100002)(106356001)(97736004)(2501003)(66066001)(8936002)(1076002)(99286004)(2906002)(36756003)(86362001)(14454004)(6506007)(110136005)(4326008)(102836004)(6512007)(81156014)(305945005)(81166006)(7736002)(8676002)(53936002)(72206003)(59450400001)(6436002)(316002)(478600001)(76176011)(25786009)(6486002)(26005)(54906003)(3280700002)(186003)(107886003)(22906009)(217873001);DIR:OUT;SFP:1102;SCL:1;SRVR:MW2PR2101MB0970;H:MW2PR2101MB1034.namprd21.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;A:1;MX:1;LANG:en; x-microsoft-antispam-message-info: liFLURd4KkNov6c9uNh87NTOyl95ihBTOMbZfiFCmpHL7NqkBumj7qW3Gp4qzO6pYMeeu+yqFRhy50G12uCMaW5V/gfs0gAwGb8Fl/2oyPbtfs8BjTSvenT00OiLe+QqIXJW/ViAPabg4dCYxl8AqrLDaatEspsrlI+owKzzfrQ= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: bf6f0139-b68f-4afd-db06-08d5815590ce X-MS-Exchange-CrossTenant-originalarrivaltime: 03 Mar 2018 22:24:20.4784 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW2PR2101MB0970 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: "Paul E. McKenney" [ Upstream commit 2fe2582649aa2355f79acddb86bd4d6c5363eb63 ] The rcutorture test suite occasionally provokes a splat due to invoking rt_mutex_lock() which needs to boost the priority of a task currently sitting on a runqueue that belongs to an offline CPU: WARNING: CPU: 0 PID: 12 at /home/paulmck/public_git/linux-rcu/arch/x86/kern= el/smp.c:128 native_smp_send_reschedule+0x37/0x40 Modules linked in: CPU: 0 PID: 12 Comm: rcub/7 Not tainted 4.14.0-rc4+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1u= buntu1 04/01/2014 task: ffff9ed3de5f8cc0 task.stack: ffffbbf80012c000 RIP: 0010:native_smp_send_reschedule+0x37/0x40 RSP: 0018:ffffbbf80012fd10 EFLAGS: 00010082 RAX: 000000000000002f RBX: ffff9ed3dd9cb300 RCX: 0000000000000004 RDX: 0000000080000004 RSI: 0000000000000086 RDI: 00000000ffffffff RBP: ffffbbf80012fd10 R08: 000000000009da7a R09: 0000000000007b9d R10: 0000000000000001 R11: ffffffffbb57c2cd R12: 000000000000000d R13: ffff9ed3de5f8cc0 R14: 0000000000000061 R15: ffff9ed3ded59200 FS: 0000000000000000(0000) GS:ffff9ed3dea00000(0000) knlGS:000000000000000= 0 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000080686f0 CR3: 000000001b9e0000 CR4: 00000000000006f0 Call Trace: resched_curr+0x61/0xd0 switched_to_rt+0x8f/0xa0 rt_mutex_setprio+0x25c/0x410 task_blocks_on_rt_mutex+0x1b3/0x1f0 rt_mutex_slowlock+0xa9/0x1e0 rt_mutex_lock+0x29/0x30 rcu_boost_kthread+0x127/0x3c0 kthread+0x104/0x140 ? rcu_report_unblock_qs_rnp+0x90/0x90 ? kthread_create_on_node+0x40/0x40 ret_from_fork+0x22/0x30 Code: f0 00 0f 92 c0 84 c0 74 14 48 8b 05 34 74 c5 00 be fd 00 00 00 ff 90 = a0 00 00 00 5d c3 89 fe 48 c7 c7 a0 c6 fc b9 e8 d5 b5 06 00 <0f> ff 5d c3 0= f 1f 44 00 00 8b 05 a2 d1 13 02 85 c0 75 38 55 48 But the target task's priority has already been adjusted, so the only purpose of switched_to_rt() invoking resched_curr() is to wake up the CPU running some task that needs to be preempted by the boosted task. But the CPU is offline, which presumably means that the task must be migrated to some other CPU, and that this other CPU will undertake any needed preemption at the time of migration. Because the runqueue lock is held when resched_curr() is invoked, we know that the boosted task cannot go anywhere, so it is not necessary to invoke resched_curr() in this particular case. This commit therefore makes switched_to_rt() refrain from invoking resched_curr() when the target CPU is offline. Signed-off-by: Paul E. McKenney Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Sasha Levin --- kernel/sched/rt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 3401f588c916..89a086ed2b16 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2218,7 +2218,7 @@ static void switched_to_rt(struct rq *rq, struct task= _struct *p) if (p->nr_cpus_allowed > 1 && rq->rt.overloaded) queue_push_tasks(rq); #endif /* CONFIG_SMP */ - if (p->prio < rq->curr->prio) + if (p->prio < rq->curr->prio && cpu_online(cpu_of(rq))) resched_curr(rq); } } --=20 2.14.1