From nobody Sun Feb 8 01:21:30 2026 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 4D289EB64DA for ; Sat, 24 Jun 2023 09:23:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231421AbjFXJWs (ORCPT ); Sat, 24 Jun 2023 05:22:48 -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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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; } =20 + 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); --=20 2.17.1