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[2620:137:e000::1:20]) by mx.google.com with ESMTP id 20-20020a630f54000000b00551bb2b99besi1121805pgp.85.2023.06.24.02.25.40; Sat, 24 Jun 2023 02:25:54 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=huawei.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232440AbjFXJWr (ORCPT + 99 others); Sat, 24 Jun 2023 05:22:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51460 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231609AbjFXJWi (ORCPT ); Sat, 24 Jun 2023 05:22:38 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C10F10FD for ; Sat, 24 Jun 2023 02:22:36 -0700 (PDT) Received: from kwepemi500017.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Qp7qD6ww7ztQcG; Sat, 24 Jun 2023 17:19:52 +0800 (CST) Received: from ubuntu1804.huawei.com (10.67.175.30) by kwepemi500017.china.huawei.com (7.221.188.110) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Sat, 24 Jun 2023 17:22:32 +0800 From: Hui Tang To: , , , CC: , , , Subject: [PATCH] sched/rt: Fix possible warn when push_rt_task Date: Sat, 24 Jun 2023 17:21:30 +0800 Message-ID: <20230624092130.174409-1-tanghui20@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.67.175.30] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemi500017.china.huawei.com (7.221.188.110) X-CFilter-Loop: Reflected X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1769575552326544788?= X-GMAIL-MSGID: =?utf-8?q?1769575552326544788?= A warn may be triggered during reboot, as follows: reboot ->kernel_restart ->machine_restart ->smp_send_stop --- ipi handler set_cpu_online(cpu, false) balance_callback -> __balance_callback ->push_rt_task -> find_lock_lowest_rq --- offline cpu in vec->mask not be cleared -> find_lowest_rq -> cpupri_find -> cpupri_find_fitness -> __cpupri_find [cpumask_and(..., vec->mask)] -> set_task_cpu(next_task, lowest_rq->cpu) --- WARN_ON(!oneline(cpu) So add !cpu_online(lowest_rq->cpu) check before set_task_cpu(). The fix does not completely fix the problem, since cpu_online_mask may be cleared after check. Fixes: 4ff9083b8a9a8 ("sched/core: WARN() when migrating to an offline CPU") Signed-off-by: Hui Tang --- kernel/sched/rt.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 00e0e5074115..852ef18b6a50 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2159,6 +2159,9 @@ static int push_rt_task(struct rq *rq, bool pull) goto retry; } + if (unlikely(!cpu_online(lowest_rq->cpu))) + goto out; + deactivate_task(rq, next_task, 0); set_task_cpu(next_task, lowest_rq->cpu); activate_task(lowest_rq, next_task, 0);