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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_MUTT autolearn=ham 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 4E492C43615 for ; Fri, 24 Aug 2018 14:31:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0980A2156B for ; Fri, 24 Aug 2018 14:31:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="UP7PoMx7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0980A2156B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727147AbeHXSFz (ORCPT ); Fri, 24 Aug 2018 14:05:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:54462 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726277AbeHXSFz (ORCPT ); Fri, 24 Aug 2018 14:05:55 -0400 Received: from localhost (LFbn-NCY-1-241-207.w83-194.abo.wanadoo.fr [83.194.85.207]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 97AAF208B7; Fri, 24 Aug 2018 14:30:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1535121060; bh=hsTsbIMfF+6ijLVnBqttEZiXCMTpgyfadtbOuAHc1mE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UP7PoMx7VYNVwp2k5J/BVGuoP5fH+Y5j22rUuNc0qWNA+UDAgeAVeBFNiliBuFjYj REqHTiw3KZ9m848Ha5+UStemSRPcQ7g2rRqj8/g+P70oHNoSpfJHjuo+2NEWbvTZGa Czj624fKPpWgWovvW1KFkLgnqu33idusd65ZYN08= Date: Fri, 24 Aug 2018 16:30:57 +0200 From: Frederic Weisbecker To: Thomas Gleixner Cc: Heiner Kallweit , Anna-Maria Gleixner , Linux Kernel Mailing List , Grygorii Strashko Subject: Re: Fix 80d20d35af1e ("nohz: Fix local_timer_softirq_pending()") may have revealed another problem Message-ID: <20180824143056.GC2730@lerouge> References: <8b93f213-fe67-f132-f3f5-5b17995ec63d@gmail.com> <20180824041245.GA2730@lerouge> <67ce38dc-1f00-55c6-f9ae-2dec00172cf6@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 24, 2018 at 10:01:35AM +0200, Thomas Gleixner wrote: > On Fri, 24 Aug 2018, Heiner Kallweit wrote: > > On 24.08.2018 06:12, Frederic Weisbecker wrote: > > > On Thu, Aug 16, 2018 at 08:13:03AM +0200, Heiner Kallweit wrote: > > >> Recently I started to get warning "NOHZ: local_softirq_pending 202" and > > >> I think it's related to mentioned commit (didn't bisect it yet). > > >> See log from suspending. > > >> > > >> I have no reason to think the fix is wrong, it may just have revealed > > >> another issue which existed before and was hidden by the bug. > > >> > > >> Rgds, Heiner > > >> > > >> [ 75.073353] random: crng init done > > >> [ 75.073402] random: 7 urandom warning(s) missed due to ratelimiting > > >> [ 78.619564] PM: suspend entry (deep) > > >> [ 78.619675] PM: Syncing filesystems ... done. > > >> [ 78.653684] Freezing user space processes ... (elapsed 0.002 seconds) done. > > >> [ 78.656094] OOM killer disabled. > > >> [ 78.656113] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done. > > >> [ 78.658177] Suspending console(s) (use no_console_suspend to debug) > > >> [ 78.663066] nuvoton-cir 00:07: disabled > > >> [ 78.671817] sd 0:0:0:0: [sda] Synchronizing SCSI cache > > >> [ 78.672210] sd 0:0:0:0: [sda] Stopping disk > > >> [ 78.786651] ACPI: Preparing to enter system sleep state S3 > > >> [ 78.789613] PM: Saving platform NVS memory > > >> [ 78.789759] Disabling non-boot CPUs ... > > >> [ 78.805154] NOHZ: local_softirq_pending 202 > > >> [ 78.805182] NOHZ: local_softirq_pending 202 > > >> [ 78.807102] smpboot: CPU 1 is now offline > > > > > > I've tried to reproduce with suspend on disk but got unsuccessful. > > > > > > A small question as I see someone is having a similar issue with a stable > > > release only. On which kernel did you trigger that: upstream or stable? > > > > > > I'll continue investigating. > > > > > > Thanks. > > > > > Affected is recent linux-next, after the commit mentioned in the subject. > > I can work around the warning (not sure whether it's a proper fix), > > see here: > > https://lkml.org/lkml/2018/8/18/272 > > Can you try the one I posted in this thread: > > https://lkml.kernel.org/r/alpine.DEB.2.21.1808240851420.1668@nanos.tec.linutronix.de > > Also below for reference. > > Thanks, > > tglx > > 8<---------------- > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index 5b33e2f5c0ed..6aab9d54a331 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c > @@ -888,7 +888,7 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) > if (unlikely(local_softirq_pending() && cpu_online(cpu))) { > static int ratelimit; > > - if (ratelimit < 10 && > + if (ratelimit < 10 && !in_softirq() && > (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { > pr_warn("NOHZ: local_softirq_pending %02x\n", > (unsigned int) local_softirq_pending()); I fear it may not work in his case because it happens in -next and we don't stop the idle tick from IRQ tail anymore. So we shouldn't be interrupting a softirq in this path. Still it's worth trying, I may well be missing something. Thanks.