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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 64161CA9EAF for ; Mon, 21 Oct 2019 13:40:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 36D8E214B2 for ; Mon, 21 Oct 2019 13:40:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729560AbfJUNko (ORCPT ); Mon, 21 Oct 2019 09:40:44 -0400 Received: from mx2.suse.de ([195.135.220.15]:56296 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729539AbfJUNkl (ORCPT ); Mon, 21 Oct 2019 09:40:41 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id AAE91B233; Mon, 21 Oct 2019 13:40:39 +0000 (UTC) Date: Mon, 21 Oct 2019 15:40:38 +0200 From: Petr Mladek To: Peter Zijlstra Cc: Thomas Gleixner , Ingo Molnar , Laurence Oberman , Vincent Whitchurch , Michal Hocko , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] watchdog/softlockup: Report the same softlockup regularly Message-ID: <20191021134038.fz2cdpxrd3p3yhb7@pathway.suse.cz> References: <20190819104732.20966-1-pmladek@suse.com> <20190819104732.20966-3-pmladek@suse.com> <20191021124339.GE1817@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191021124339.GE1817@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20170912 (1.9.0) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 2019-10-21 14:43:39, Peter Zijlstra wrote: > On Mon, Aug 19, 2019 at 12:47:31PM +0200, Petr Mladek wrote: > > Softlockup report means that there is no progress on the given CPU. It > > might be a "short" affair where the system gets recovered. But often > > the system stops being responsive and need to get rebooted. > > > > The softlockup might be root of the problems or just a symptom. It might > > be a deadlock, livelock, or often repeated state. > > > > Regular reports help to distinguish different situations. Fortunately, > > the watchdog is finally able to show correct information how long > > softlockup_fn() was not scheduled. > > > > Report before this patch: > > > > [ 320.248948] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4916] > > > > And after this patch: > > > > [ 480.372418] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4943] > > [ 508.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 52s! [cat:4943] > > [ 548.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 89s! [cat:4943] > > [ 576.372351] watchdog: BUG: soft lockup - CPU#2 stuck for 115s! [cat:4943] > > > > Note that the horrible code never really worked before the accounting > > was fixed. The last working timestamp was regularly lost by the many > > touch*watchdog() calls. > > So what's the point of patch 1? Just confusing people? I was not sure what was the expected behavior. The code actually looked like only the first report was wanted. But it probably never worked that way. Should I squash the two patches and send it again, please? Best Regards, Petr