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=-18.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 A189AC433E2 for ; Tue, 1 Sep 2020 07:04:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74F212071B for ; Tue, 1 Sep 2020 07:04:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727052AbgIAHEN (ORCPT ); Tue, 1 Sep 2020 03:04:13 -0400 Received: from mga01.intel.com ([192.55.52.88]:31873 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726122AbgIAHEL (ORCPT ); Tue, 1 Sep 2020 03:04:11 -0400 IronPort-SDR: ZMtPtc26BJ17MpnKYf/1RKl5SyDtCW7td/N0GiokmpGeugIH+tkfknZ12NYQH0KwceYhh5F1jY uc2kbXMt+Kig== X-IronPort-AV: E=McAfee;i="6000,8403,9730"; a="175163124" X-IronPort-AV: E=Sophos;i="5.76,378,1592895600"; d="scan'208";a="175163124" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Sep 2020 00:04:09 -0700 IronPort-SDR: efF1CteDSvGUjeuCqyhMEUNm9cFV4TnP7lq8jUVXOjIXznGnws6g1EdUdV4PMWcoPSQL7jVqCX 5ZCmFbREJVsw== X-IronPort-AV: E=Sophos;i="5.76,378,1592895600"; d="scan'208";a="502140536" Received: from shao2-debian.sh.intel.com (HELO [10.239.13.3]) ([10.239.13.3]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Sep 2020 00:04:06 -0700 Subject: Re: [LKP] Re: [rcuperf] 4e88ec4a9e: UBSAN:division-overflow_in_arch/x86/include/asm/div64.h To: paulmck@kernel.org, kernel test robot Cc: Ingo Molnar , LKML , lkp@lists.01.org References: <20200831120122.GH4299@shao2-debian> <20200831155037.GZ2855@paulmck-ThinkPad-P72> From: Rong Chen Message-ID: <649fd850-602f-7f0d-d286-73a8dd88ad6d@intel.com> Date: Tue, 1 Sep 2020 15:03:28 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20200831155037.GZ2855@paulmck-ThinkPad-P72> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/31/20 11:50 PM, Paul E. McKenney wrote: > On Mon, Aug 31, 2020 at 08:01:22PM +0800, kernel test robot wrote: >> Greeting, >> >> FYI, we noticed the following commit (built with gcc-9): >> >> commit: 4e88ec4a9eb17527e640b063f79e5b875733eb53 ("rcuperf: Change rcuperf to rcuscale") >> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master >> >> >> in testcase: trinity >> with following parameters: >> >> runtime: 300s >> >> test-description: Trinity is a linux system call fuzz tester. >> test-url: http://codemonkey.org.uk/projects/trinity/ >> >> >> on test machine: qemu-system-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 8G >> >> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): >> >> >> +---------------------------------------------------------+------------+------------+ >> | | 65bd77f554 | 4e88ec4a9e | >> +---------------------------------------------------------+------------+------------+ >> | boot_successes | 13 | 0 | >> | boot_failures | 0 | 14 | >> | UBSAN:division-overflow_in_arch/x86/include/asm/div64.h | 0 | 14 | >> | error:#[##] | 0 | 14 | >> | EIP:main_func.cold | 0 | 14 | >> | Kernel_panic-not_syncing:Fatal_exception | 0 | 14 | >> +---------------------------------------------------------+------------+------------+ >> >> >> If you fix the issue, kindly add following tag >> Reported-by: kernel test robot > Does the patch below fix this for you? Yes, this patch can fix the issue, and nreaders was adjusted to 1: [    5.953645] The force parameter has not been set to 1. The Iris poweroff handler will not be installed. [   12.546587] rcu-ref-scale: --- Start of test:  verbose=0 shutdown=1 holdoff=10 loops=10000 nreaders=-1 nruns=30 readdelay=0 [   12.561495] ------------[ cut here ]------------ [   12.562016] ref_scale_init: nreaders = 0, adjusted to 1 [   12.562601] WARNING: CPU: 0 PID: 1 at kernel/rcu/refscale.c:684 ref_scale_init+0x653/0x80 Best Regards, Rong Chen > > Thanx, Paul > > ------------------------------------------------------------------------ > > commit d301e320e952e2e604d83d9540e52510b0eb3d94 > Author: Paul E. McKenney > Date: Thu Aug 27 09:58:19 2020 -0700 > > refscale: Bounds-check module parameters > > The default value for refscale.nreaders is -1, which results in the code > setting the value to three-quarters of the number of CPUs. On single-CPU > systems, this results in three-quarters of the value one, which the C > language's integer arithmetic rounds to zero. This in turn results in > a divide-by-zero error. > > This commit therefore adds bounds checking to the refscale module > parameters, so that if they are less than one, they are set to the > value one. > > Reported-by: kernel test robot > Signed-off-by: Paul E. McKenney > > diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c > index 952595c..fb5f20d 100644 > --- a/kernel/rcu/refscale.c > +++ b/kernel/rcu/refscale.c > @@ -681,6 +681,12 @@ ref_scale_init(void) > // Reader tasks (default to ~75% of online CPUs). > if (nreaders < 0) > nreaders = (num_online_cpus() >> 1) + (num_online_cpus() >> 2); > + if (WARN_ONCE(loops <= 0, "%s: loops = %ld, adjusted to 1\n", __func__, loops)) > + loops = 1; > + if (WARN_ONCE(nreaders <= 0, "%s: nreaders = %d, adjusted to 1\n", __func__, nreaders)) > + nreaders = 1; > + if (WARN_ONCE(nruns <= 0, "%s: nruns = %d, adjusted to 1\n", __func__, nruns)) > + nruns = 1; > reader_tasks = kcalloc(nreaders, sizeof(reader_tasks[0]), > GFP_KERNEL); > if (!reader_tasks) { > _______________________________________________ > LKP mailing list -- lkp@lists.01.org > To unsubscribe send an email to lkp-leave@lists.01.org