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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 B9AE6C11F68 for ; Tue, 29 Jun 2021 02:34:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A5E5D61D00 for ; Tue, 29 Jun 2021 02:34:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231799AbhF2Cgt (ORCPT ); Mon, 28 Jun 2021 22:36:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:57480 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231219AbhF2Cgs (ORCPT ); Mon, 28 Jun 2021 22:36:48 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2887861D01; Tue, 29 Jun 2021 02:34:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1624934061; bh=2iRfE0JTm6wyFLp7XVFXiRgUs+z0poBaTfg/hkmSe8o=; h=Date:From:To:Subject:In-Reply-To:From; b=U/qDB6zwY4nt6jSekUXJUkkKy9UUvJtVfD1da5IzGmwqgx2NZgAeSl6bEQ//bHNWc h2I5pkH4b6K8hthZw3LY0GUEGSQFq5MOL+ga7i/8Fp7NVy5KjaLzI0W3pvOUDMTB0P mqNzGXR1MCGBrAIX0Qh5JnJKbcDsy/wjGBSPqZiQ= Date: Mon, 28 Jun 2021 19:34:20 -0700 From: Andrew Morton To: akpm@linux-foundation.org, corbet@lwn.net, gpiccoli@canonical.com, joe@perches.com, keescook@chromium.org, linux-mm@kvack.org, mchehab+huawei@kernel.org, mm-commits@vger.kernel.org, pmladek@suse.com, qais.yousef@arm.com, rdunlap@infradead.org, santosh@fossix.org, steve@sk2.org, torvalds@linux-foundation.org, vbabka@suse.cz, wangqing@vivo.com Subject: [patch 020/192] doc: watchdog: modify the explanation related to watchdog thread Message-ID: <20210629023420.2GMMUS9s8%akpm@linux-foundation.org> In-Reply-To: <20210628193256.008961950a714730751c1423@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Wang Qing Subject: doc: watchdog: modify the explanation related to watchdog thread "watchdog/%u" threads has be replaced by cpu_stop_work. The current description is extremely misleading. Link: https://lkml.kernel.org/r/1619687073-24686-4-git-send-email-wangqing@vivo.com Signed-off-by: Wang Qing Reviewed-by: Petr Mladek Cc: "Guilherme G. Piccoli" Cc: Joe Perches Cc: Jonathan Corbet Cc: Kees Cook Cc: Mauro Carvalho Chehab Cc: Qais Yousef Cc: Randy Dunlap Cc: Santosh Sivaraj Cc: Stephen Kitt Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- Documentation/admin-guide/lockup-watchdogs.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/Documentation/admin-guide/lockup-watchdogs.rst~doc-watchdog-modify-the-explanation-related-to-watchdog-thread +++ a/Documentation/admin-guide/lockup-watchdogs.rst @@ -39,7 +39,7 @@ in principle, they should work in any ar subsystems are present. A periodic hrtimer runs to generate interrupts and kick the watchdog -task. An NMI perf event is generated every "watchdog_thresh" +job. An NMI perf event is generated every "watchdog_thresh" (compile-time initialized to 10 and configurable through sysctl of the same name) seconds to check for hardlockups. If any CPU in the system does not receive any hrtimer interrupt during that time the @@ -47,7 +47,7 @@ does not receive any hrtimer interrupt d generate a kernel warning or call panic, depending on the configuration. -The watchdog task is a high priority kernel thread that updates a +The watchdog job runs in a stop scheduling thread that updates a timestamp every time it is scheduled. If that timestamp is not updated for 2*watchdog_thresh seconds (the softlockup threshold) the 'softlockup detector' (coded inside the hrtimer callback function) _