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=-13.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 1BCBDC433E1 for ; Mon, 18 May 2020 17:49:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF83720715 for ; Mon, 18 May 2020 17:49:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="VZ/6zRNA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728876AbgERRt2 (ORCPT ); Mon, 18 May 2020 13:49:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60946 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729506AbgERRtU (ORCPT ); Mon, 18 May 2020 13:49:20 -0400 Received: from mail-pg1-x543.google.com (mail-pg1-x543.google.com [IPv6:2607:f8b0:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 15AEEC061A0C for ; Mon, 18 May 2020 10:49:20 -0700 (PDT) Received: by mail-pg1-x543.google.com with SMTP id r10so5175030pgv.8 for ; Mon, 18 May 2020 10:49:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=mBq4CNh2SzaiNVBNhEkzgkxU7yRKv+pxY1QX3ny6bNo=; b=VZ/6zRNAtX7ZLlIID1QWRgdZtiIeGPTy6KpLomMn7JqqlM9TYujBoe1ZNgZVDIwquw ALYqr3PEcui0ZwjYYSnWjyK6pf8VE9zmUuIuAtQFogiF0ec5vn+LTgNNgZabT18V1qGp fYcHYtQePf5E8AdCeKiarqvj8k7FWkDfvIqOafYwf4u6ghZ2Va4dEK/DOYyuzoIGIp1x nyn618v+L6curDrasU9mH0v11URYueVTIs5e7vyBLELrRyQyH/ZtAOW6OdrFc6E8HS/r 1d9QyjXSKUzE6Hd43GT/swjkdoEgDK36woYmEOjAy3Wzbmc580F9wlAufVZmlJCooCER ygQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=mBq4CNh2SzaiNVBNhEkzgkxU7yRKv+pxY1QX3ny6bNo=; b=qazfvMXltUb9TmOO9QYMhrVUe1iU1FAF2by0XXLu7wHcCUCchx3CJSp0Zn5mIcrWdW zj4Gg+fvHXFLIZyvmfz3BKa8AotZ+xL1xjXQ7jeugkrgWUadjgApEqR+ZTkp/KzlQTzU 5RkcyqeUY+5QhZl1ngS/SVL9ILH9i+/8I+EM5JT4BNbHFBZd4LEf0+Fqe6wHOceXNnLv myvDCw+IaWM9LkwF/NAUG8g84F/3oOFCICSVmQizKrjT4HzuKoeX8By/7eY7MWgTHkOO Sf+4SRzpBhPu7XSVN7W7oVKgupKOUREcZf1PFnLgBu1m84owpGYi+eE4i0jijkmJ6w5J ZeMw== X-Gm-Message-State: AOAM531jqbf4OWiuOXJqT+4wV6xAT0AnGN4JA5pUgAu3P+ppBrdeoIww 3Hgt9fu4gbmv02zD3nG6zqi1qbqntrDsPsGYhZEjaQ== X-Google-Smtp-Source: ABdhPJxRHZLfRdK8uwwpMwsbOhVoF9vG5SJy734z8XHqMzN8eGkBO6NS7OWznhB++dzCLKoA34gxjZ8Pn9+T4BRCXLE= X-Received: by 2002:a63:d010:: with SMTP id z16mr5906980pgf.381.1589824159213; Mon, 18 May 2020 10:49:19 -0700 (PDT) MIME-Version: 1.0 References: <20200517011732.GE24705@shao2-debian> <20200517034739.GO2869@paulmck-ThinkPad-P72> In-Reply-To: From: Nick Desaulniers Date: Mon, 18 May 2020 10:49:08 -0700 Message-ID: Subject: Re: [rcu] 2f08469563: BUG:kernel_reboot-without-warning_in_boot_stage To: Marco Elver Cc: Kan Liang , clang-built-linux , kasan-dev , kernel test robot , Peter Zijlstra , LKML , LKP , "Paul E. McKenney" , Dmitry Vyukov , Alexander Potapenko , Andrey Konovalov Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 18, 2020 at 7:34 AM Marco Elver wrote: > > On Mon, 18 May 2020 at 14:44, Marco Elver wrote: > > > > [+Cc clang-built-linux FYI] > > > > On Mon, 18 May 2020 at 12:11, Marco Elver wrote: > > > > > > On Sun, 17 May 2020 at 05:47, Paul E. McKenney wrote: > > > > > > > > On Sun, May 17, 2020 at 09:17:32AM +0800, kernel test robot wrote: > > > > > Greeting, > > > > > > > > > > FYI, we noticed the following commit (built with clang-11): > > > > > > > > > > commit: 2f08469563550d15cb08a60898d3549720600eee ("rcu: Mark rcu_state.ncpus to detect concurrent writes") > > > > > https://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.git dev.2020.05.14c > > > > > > > > > > in testcase: boot > > > > > > > > > > on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 8G > > > > > > > > > > caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): > > > > > > > > > > > > > > > > > > > > > > > > > If you fix the issue, kindly add following tag > > > > > Reported-by: kernel test robot > > > > > > > > > > > > > > > [ 0.054943] BRK [0x05204000, 0x05204fff] PGTABLE > > > > > [ 0.061181] BRK [0x05205000, 0x05205fff] PGTABLE > > > > > [ 0.062403] BRK [0x05206000, 0x05206fff] PGTABLE > > > > > [ 0.065200] RAMDISK: [mem 0x7a247000-0x7fffffff] > > > > > [ 0.067344] ACPI: Early table checksum verification disabled > > > > > BUG: kernel reboot-without-warning in boot stage > > > > > > > > I am having some difficulty believing that this commit is at fault given > > > > that the .config does not list CONFIG_KCSAN=y, but CCing Marco Elver > > > > for his thoughts. Especially given that I have never built with clang-11. > > > > > > > > But this does invoke ASSERT_EXCLUSIVE_WRITER() in early boot from > > > > rcu_init(). Might clang-11 have objections to early use of this macro? > > > > > > The macro is a noop without KCSAN. I think the bisection went wrong. > > > > > > I am able to reproduce a reboot-without-warning when building with > > > Clang 11 and the provided config. I did a bisect, starting with v5.6 > > > (good), and found this: > > > - Since v5.6, first bad commit is > > > 20e2aa812620439d010a3f78ba4e05bc0b3e2861 (Merge tag > > > 'perf-urgent-2020-04-12' of > > > git://git.kernel.org/pub/scm/linux/kernel//git/tip/tip) > > > - The actual commit that introduced the problem is > > > 2b3b76b5ec67568da4bb475d3ce8a92ef494b5de (perf/x86/intel/uncore: Add > > > Ice Lake server uncore support) -- reverting it fixes the problem. > > Some more clues: > > 1. I should have noticed that this uses CONFIG_KASAN=y. Thanks for the report, testing, and bisection. I don't see any smoking gun in the code. https://godbolt.org/z/qbK26r > > 2. Something about function icx_uncore_mmio_init(). Making it a noop > also makes the issue go away. > > 3. Leaving icx_uncore_mmio_init() a noop but removing the 'static' > from icx_mmio_uncores also presents the issue. So this seems to be > something about how/where icx_mmio_uncores is allocated. Can you share the disassembly of icx_uncore_mmio_init() in the given configuration? -- Thanks, ~Nick Desaulniers From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============0290597936124229648==" MIME-Version: 1.0 From: Nick Desaulniers To: lkp@lists.01.org Subject: Re: [rcu] 2f08469563: BUG:kernel_reboot-without-warning_in_boot_stage Date: Mon, 18 May 2020 10:49:08 -0700 Message-ID: In-Reply-To: List-Id: --===============0290597936124229648== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On Mon, May 18, 2020 at 7:34 AM Marco Elver wrote: > > On Mon, 18 May 2020 at 14:44, Marco Elver wrote: > > > > [+Cc clang-built-linux FYI] > > > > On Mon, 18 May 2020 at 12:11, Marco Elver wrote: > > > > > > On Sun, 17 May 2020 at 05:47, Paul E. McKenney = wrote: > > > > > > > > On Sun, May 17, 2020 at 09:17:32AM +0800, kernel test robot wrote: > > > > > Greeting, > > > > > > > > > > FYI, we noticed the following commit (built with clang-11): > > > > > > > > > > commit: 2f08469563550d15cb08a60898d3549720600eee ("rcu: Mark rcu_= state.ncpus to detect concurrent writes") > > > > > https://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.gi= t dev.2020.05.14c > > > > > > > > > > in testcase: boot > > > > > > > > > > on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge = -smp 2 -m 8G > > > > > > > > > > caused below changes (please refer to attached dmesg/kmsg for ent= ire log/backtrace): > > > > > > > > > > > > > > > > > > > > > > > > > If you fix the issue, kindly add following tag > > > > > Reported-by: kernel test robot > > > > > > > > > > > > > > > [ 0.054943] BRK [0x05204000, 0x05204fff] PGTABLE > > > > > [ 0.061181] BRK [0x05205000, 0x05205fff] PGTABLE > > > > > [ 0.062403] BRK [0x05206000, 0x05206fff] PGTABLE > > > > > [ 0.065200] RAMDISK: [mem 0x7a247000-0x7fffffff] > > > > > [ 0.067344] ACPI: Early table checksum verification disabled > > > > > BUG: kernel reboot-without-warning in boot stage > > > > > > > > I am having some difficulty believing that this commit is at fault = given > > > > that the .config does not list CONFIG_KCSAN=3Dy, but CCing Marco El= ver > > > > for his thoughts. Especially given that I have never built with cl= ang-11. > > > > > > > > But this does invoke ASSERT_EXCLUSIVE_WRITER() in early boot from > > > > rcu_init(). Might clang-11 have objections to early use of this ma= cro? > > > > > > The macro is a noop without KCSAN. I think the bisection went wrong. > > > > > > I am able to reproduce a reboot-without-warning when building with > > > Clang 11 and the provided config. I did a bisect, starting with v5.6 > > > (good), and found this: > > > - Since v5.6, first bad commit is > > > 20e2aa812620439d010a3f78ba4e05bc0b3e2861 (Merge tag > > > 'perf-urgent-2020-04-12' of > > > git://git.kernel.org/pub/scm/linux/kernel//git/tip/tip) > > > - The actual commit that introduced the problem is > > > 2b3b76b5ec67568da4bb475d3ce8a92ef494b5de (perf/x86/intel/uncore: Add > > > Ice Lake server uncore support) -- reverting it fixes the problem. > > Some more clues: > > 1. I should have noticed that this uses CONFIG_KASAN=3Dy. Thanks for the report, testing, and bisection. I don't see any smoking gun in the code. https://godbolt.org/z/qbK26r > > 2. Something about function icx_uncore_mmio_init(). Making it a noop > also makes the issue go away. > > 3. Leaving icx_uncore_mmio_init() a noop but removing the 'static' > from icx_mmio_uncores also presents the issue. So this seems to be > something about how/where icx_mmio_uncores is allocated. Can you share the disassembly of icx_uncore_mmio_init() in the given configuration? -- = Thanks, ~Nick Desaulniers --===============0290597936124229648==--