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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 5954BCA9EAF for ; Mon, 21 Oct 2019 12:43:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 29BFC21BE5 for ; Mon, 21 Oct 2019 12:43:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="IK53TzyG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728760AbfJUMnq (ORCPT ); Mon, 21 Oct 2019 08:43:46 -0400 Received: from merlin.infradead.org ([205.233.59.134]:55866 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728744AbfJUMnp (ORCPT ); Mon, 21 Oct 2019 08:43:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=W208iAKhnrpYar+NC/MwFXKY50BC0Ke2j8viCg/6BJc=; b=IK53TzyGP6fZNTe/sYUuLGQlr KoMfMOuvY283bNFipmCZ+0ZkKLFxg7TBaXLNCm6pkTmBSooLGXO+Nmm6rplsQpux0hdnkBjVtk91x /3E5InJBbufuxowUc2iYB+e9yZhryGWuBbEcMdSkX97rF/nknRTnC1E9aGWXfvFNfErQ+XeMiFkRS f+7J2agIavBb+1yjXvoD3ipae+YfLUBF5qfkm1YbztjlLAL8xNDYRf1MJ808tGghTKXNf9/4mUyNW INzo+CZKGm7vxfyvW8dREntcAteccVimFnZjid7VZs/jzAu4lN5DdzjB2+GHvq6eojhmuU9gAvdvV Z6jpsfSuA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iMX2C-0004WQ-MF; Mon, 21 Oct 2019 12:43:40 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 56472301124; Mon, 21 Oct 2019 14:42:42 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6D5E12022BA17; Mon, 21 Oct 2019 14:43:39 +0200 (CEST) Date: Mon, 21 Oct 2019 14:43:39 +0200 From: Peter Zijlstra To: Petr Mladek 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: <20191021124339.GE1817@hirez.programming.kicks-ass.net> References: <20190819104732.20966-1-pmladek@suse.com> <20190819104732.20966-3-pmladek@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190819104732.20966-3-pmladek@suse.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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?