From patchwork Fri Apr 30 05:54:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12232327 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=-15.7 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,URIBL_BLOCKED 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 B474CC433B4 for ; Fri, 30 Apr 2021 05:54:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4984C61459 for ; Fri, 30 Apr 2021 05:54:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4984C61459 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DC8286B006E; Fri, 30 Apr 2021 01:54:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D79346B0098; Fri, 30 Apr 2021 01:54:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C3F796B0099; Fri, 30 Apr 2021 01:54:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0107.hostedemail.com [216.40.44.107]) by kanga.kvack.org (Postfix) with ESMTP id A87826B006E for ; Fri, 30 Apr 2021 01:54:25 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 776EB364C for ; Fri, 30 Apr 2021 05:54:25 +0000 (UTC) X-FDA: 78087968490.13.AEAB6AB Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf18.hostedemail.com (Postfix) with ESMTP id F26492000242 for ; Fri, 30 Apr 2021 05:54:26 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 1D81161458; Fri, 30 Apr 2021 05:54:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1619762064; bh=wB9PlAoNJkpYo1ZYEHmQWRRQd89Mjrz5CyST9KkT164=; h=Date:From:To:Subject:In-Reply-To:From; b=rAy8+uy0+dTl2AfxQ3ikfSySUCJHXaEQyquDIGQ7flrGgvcFasdQmQRrIg4yn58kt 1NcNfikwnr6VI7vk8Z0/iZGCpdZVQHSihqTOTCzmGjfyA5V80jqB4IncrEbeKlOI0L Eq8QeKPB4XJFnYFpm9bnbJZ2rVdlDw9PkG20xTAI= Date: Thu, 29 Apr 2021 22:54:23 -0700 From: Andrew Morton To: akpm@linux-foundation.org, linux-mm@kvack.org, loberman@redhat.com, mhocko@suse.com, mingo@kernel.org, mm-commits@vger.kernel.org, peterz@infradead.org, pmladek@suse.com, tglx@linutronix.de, torvalds@linux-foundation.org, vincent.whitchurch@axis.com Subject: [patch 023/178] watchdog: explicitly update timestamp when reporting softlockup Message-ID: <20210430055423.pnd2rwY-w%akpm@linux-foundation.org> In-Reply-To: <20210429225251.02b6386d21b69255b4f6c163@linux-foundation.org> User-Agent: s-nail v14.8.16 Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=rAy8+uy0; spf=pass (imf18.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: F26492000242 X-Stat-Signature: fe8en46m8qfbi7nf15t9zafxshs6qwoe Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf18; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619762066-727700 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Petr Mladek Subject: watchdog: explicitly update timestamp when reporting softlockup The softlockup situation might stay for a long time or even forever. When it happens, the softlockup debug messages are printed in regular intervals defined by get_softlockup_thresh(). There is a mystery. The repeated message is printed after the full interval that is defined by get_softlockup_thresh(). But the timer callback is called more often as defined by sample_period. The code looks like the soflockup should get reported in every sample_period when it was once behind the thresh. It works only by chance. The watchdog is touched when printing the stall report, for example, in printk_stack_address(). Make the behavior clear and predictable by explicitly updating the timestamp in watchdog_timer_fn() when the report gets printed. Link: https://lkml.kernel.org/r/20210311122130.6788-3-pmladek@suse.com Signed-off-by: Petr Mladek Cc: Ingo Molnar Cc: Laurence Oberman Cc: Michal Hocko Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vincent Whitchurch Signed-off-by: Andrew Morton --- kernel/watchdog.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/watchdog.c~watchdog-explicitly-update-timestamp-when-reporting-softlockup +++ a/kernel/watchdog.c @@ -410,6 +410,9 @@ static enum hrtimer_restart watchdog_tim } } + /* Start period for the next softlockup warning. */ + update_touch_ts(); + pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", smp_processor_id(), duration, current->comm, task_pid_nr(current));