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_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED,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 D03ACC43142 for ; Tue, 26 Jun 2018 16:33:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8804926CEE for ; Tue, 26 Jun 2018 16:33:04 +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="IfROJ30o" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8804926CEE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.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 S1752507AbeFZQdC (ORCPT ); Tue, 26 Jun 2018 12:33:02 -0400 Received: from merlin.infradead.org ([205.233.59.134]:49202 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751980AbeFZQdB (ORCPT ); Tue, 26 Jun 2018 12:33:01 -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=2Xb50pWIHlJUmEyRzTKzn6yle+BTxGxcFHo2PrulaDs=; b=IfROJ30oJg8EfpeOPxYX7lyQp iK2qiSXmvk8H6sh1JiNZlbRu2fkalpsKCM9CMz5E53vuYdsNm/gO0t+tanU1ta0jKl94/DDtpL0Wf 4O23TzoTzYX1uj2CcoCtROC4H3bKRH2MFMXRAM2fJXf/QeXHDIBt06OffJikGFLB8cj3sBHGkVvEH s/3OiEFQFi1TqBOl3/iZ1i+1yMycL3vjVWvKZjsssUUAF8fFtgiUQ1IsHp9U5IehmuEB846A0lq1Y Mz+Jx+8FgUm93+kFh+z9EGXdiU2tc0pd7Lp5ad7heiwq7de270oP28X+PTyPugb7HW05wjbKgsTIW NG4It6nKg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fXqtl-0003Nm-5x; Tue, 26 Jun 2018 16:32:57 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 9B2402029F1D9; Tue, 26 Jun 2018 18:32:55 +0200 (CEST) Date: Tue, 26 Jun 2018 18:32:55 +0200 From: Peter Zijlstra To: Anna-Maria Gleixner Cc: linux-kernel@vger.kernel.org, "Paul E. McKenney" , Thomas Gleixner , Frederic Weisbecker Subject: Re: sched/core warning triggers on rcu torture test Message-ID: <20180626163255.GG2458@hirez.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 26, 2018 at 06:16:04PM +0200, Anna-Maria Gleixner wrote: > Hi, > > during rcu torture tests (TREE04 and TREE07) I noticed, that a > WARN_ON_ONCE() in sched core triggers on a recent 4.18-rc2 based > kernel (6f0d349d922b ("Merge > git://git.kernel.org/pub/scm/linux/kernel/git/davem/net")) as well as > on a 4.17.3. > > I'm running the tests on a machine with 144 cores: > > tools/testing/selftests/rcutorture/bin/kvm.sh --cpus 144 --duration 120 --configs "9*TREE07" > tools/testing/selftests/rcutorture/bin/kvm.sh --cpus 144 --duration 120 --configs "18*TREE04" > > > The warning was introduced by commit d84b31313ef8 ("sched/isolation: > Offload residual 1Hz scheduler tick"). > > > Output looks similar for all tests I did (this one is the output of > the 4.18-rc2 based kernel): > > WARNING: CPU: 11 PID: 906 at kernel/sched/core.c:3138 sched_tick_remote+0xb6/0xc0 That's nohz_full stuff, is that a normal part of rcutorture? In any case, is the one housekeeping CPU getting seriously overloaded or something?