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 X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41F2BC433F5 for ; Wed, 22 Sep 2021 09:52:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C10761100 for ; Wed, 22 Sep 2021 09:52:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234554AbhIVJxk (ORCPT ); Wed, 22 Sep 2021 05:53:40 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:9755 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234233AbhIVJxg (ORCPT ); Wed, 22 Sep 2021 05:53:36 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4HDtpS09vnzWMFp; Wed, 22 Sep 2021 17:50:56 +0800 (CST) Received: from kwepemm600005.china.huawei.com (7.193.23.191) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Wed, 22 Sep 2021 17:52:05 +0800 Received: from DESKTOP-R64PNO0.china.huawei.com (10.67.102.35) by kwepemm600005.china.huawei.com (7.193.23.191) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Wed, 22 Sep 2021 17:52:05 +0800 From: Jinhui Guo To: , , , CC: , Subject: [PATCH] watchdog/softlockup: Fix softlockup_stop_all() hungtask bug Date: Wed, 22 Sep 2021 17:52:02 +0800 Message-ID: <20210922095202.1655-1-guojinhui@huawei.com> X-Mailer: git-send-email 2.32.0.windows.2 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.67.102.35] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemm600005.china.huawei.com (7.193.23.191) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If NR_CPUS equal to 1, it would trigger hungtask, it can be triggered by follow command: echo 0 > /proc/sys/kernel/watchdog echo 1 > /proc/sys/kernel/watchdog The hungtask stack: __schedule schedule schedule_timeout __wait_for_common softlockup_stop_fn lockup_detector_reconfigure proc_watchdog_common proc_watchdog proc_sys_call_handler vfs_write ksys_write The watchdog_allowed_mask is completely cleared when the watchdog is disabled. But the macro for_each_cpu() assume all masks are "1" when macro NR_CPUS equal to 1. It makes watchdog_allowed_mask not work at all. Fixes: be45bf5395e0 ("watchdog/softlockup: Fix cpu_stop_queue_work() double-queue bug") Cc: Petr Mladek Reported-by: kernel test robot Signed-off-by: Jinhui Guo --- arch/x86/include/asm/smp.h | 5 +++++ include/linux/cpumask.h | 5 +++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h index 630ff08532be..f5d3ca5696b3 100644 --- a/arch/x86/include/asm/smp.h +++ b/arch/x86/include/asm/smp.h @@ -21,7 +21,12 @@ DECLARE_PER_CPU_READ_MOSTLY(int, cpu_number); static inline struct cpumask *cpu_llc_shared_mask(int cpu) { +#ifdef CONFIG_SMP return per_cpu(cpu_llc_shared_map, cpu); +#else + /* cpu_llc_shared_map is not defined while !CONFIG_SMP */ + return cpu_all_mask; +#endif } DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid); diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index 5d4d07a9e1ed..1a35dbcc397d 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -175,10 +175,11 @@ static inline int cpumask_any_distribute(const struct cpumask *srcp) return cpumask_first(srcp); } +/* It should check cpumask in some special case, such as watchdog */ #define for_each_cpu(cpu, mask) \ - for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask) + for ((cpu) = 0; (cpu) < 1 && test_bit(0, cpumask_bits(mask)); (cpu)++) #define for_each_cpu_not(cpu, mask) \ - for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask) + for ((cpu) = 0; (cpu) < 1 && !test_bit(0, cpumask_bits(mask)); (cpu)++) #define for_each_cpu_wrap(cpu, mask, start) \ for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask, (void)(start)) #define for_each_cpu_and(cpu, mask1, mask2) \ -- 2.12.3