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 5EE62C61DF4 for ; Fri, 24 Nov 2023 19:39:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345971AbjKXTji (ORCPT ); Fri, 24 Nov 2023 14:39:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345941AbjKXTjh (ORCPT ); Fri, 24 Nov 2023 14:39:37 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 671D812B for ; Fri, 24 Nov 2023 11:39:44 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 05458C433C7; Fri, 24 Nov 2023 19:39:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1700854784; bh=obyoLMHljbu8ZMk+zgpqlJffOe5w59WrJxCf2pHeQ7c=; h=Date:To:From:Subject:From; b=0RljBkqGScIRuQfGwJVItEKbjFg8R+w31VmKiyUXwa6mXtNIas89CdGVNob9S61BL CMt1lu7d5UxHJc4E3Oe8JKbJnuX7XfB8xoTyA03HmGiS9RztFH9PD9jrXvTwER3UcC moLyb/2ABTpCLj+SK2AQRfrbd5oE5GTCArnzQYk8= Date: Fri, 24 Nov 2023 11:39:43 -0800 To: mm-commits@vger.kernel.org, pmladek@suse.com, lizefan.x@bytedance.com, lecopzer.chen@mediatek.com, kernelfans@gmail.com, dianders@chromium.org, lizhe.67@bytedance.com, akpm@linux-foundation.org From: Andrew Morton Subject: + softlockup-serialized-softlockups-log.patch added to mm-nonmm-unstable branch Message-Id: <20231124193944.05458C433C7@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: softlockup: serialized softlockup's log has been added to the -mm mm-nonmm-unstable branch. Its filename is softlockup-serialized-softlockups-log.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/softlockup-serialized-softlockups-log.patch This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Li Zhe Subject: softlockup: serialized softlockup's log Date: Thu, 23 Nov 2023 16:40:22 +0800 If multiple CPUs trigger softlockup at the same time with 'softlockup_all_cpu_backtrace=0', the softlockup's logs will appear staggeredly in dmesg, which will affect the viewing of the logs for developer. Since the code path for outputting softlockup logs is not a kernel hotspot and the performance requirements for the code are not strict, locks are used to serialize the softlockup log output to improve the readability of the logs. Link: https://lkml.kernel.org/r/20231123084022.10302-1-lizhe.67@bytedance.com Signed-off-by: Li Zhe Cc: Douglas Anderson Cc: Lecopzer Chen Cc: Petr Mladek Cc: Pingfan Liu Cc: Zefan Li Signed-off-by: Andrew Morton --- kernel/watchdog.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/watchdog.c~softlockup-serialized-softlockups-log +++ a/kernel/watchdog.c @@ -448,6 +448,7 @@ static enum hrtimer_restart watchdog_tim struct pt_regs *regs = get_irq_regs(); int duration; int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; + static DEFINE_SPINLOCK(watchdog_output_lock); if (!watchdog_enabled) return HRTIMER_NORESTART; @@ -514,6 +515,7 @@ static enum hrtimer_restart watchdog_tim /* Start period for the next softlockup warning. */ update_report_ts(); + spin_lock(&watchdog_output_lock); pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", smp_processor_id(), duration, current->comm, task_pid_nr(current)); @@ -523,6 +525,7 @@ static enum hrtimer_restart watchdog_tim show_regs(regs); else dump_stack(); + spin_unlock(&watchdog_output_lock); if (softlockup_all_cpu_backtrace) { trigger_allbutcpu_cpu_backtrace(smp_processor_id()); _ Patches currently in -mm which might be from lizhe.67@bytedance.com are softlockup-serialized-softlockups-log.patch