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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 BE3F7C33CB3 for ; Tue, 14 Jan 2020 21:34:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9255C24672 for ; Tue, 14 Jan 2020 21:34:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579037648; bh=N2S7y+O790zET1Gmtmsm8tuXTXxczW82v07Ij9f4etg=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=Fvh1UwFCQb3acnwS28cd0E6C9vea2JWNFXnyH5iowNp9GgSc7KxUtJ+WtT+0tJKz4 FOtqhu3Cpw218OQEEfwDvXIm8jcPkB9++2qoKDP9g800y2+bpSczo2y9Ff4TJT0HTT moeXj322y9xBn99JpQ7NJNClmcyP7Z1GReq32Wq0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728963AbgANVeH (ORCPT ); Tue, 14 Jan 2020 16:34:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:44818 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726491AbgANVeH (ORCPT ); Tue, 14 Jan 2020 16:34:07 -0500 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A7F3924656; Tue, 14 Jan 2020 21:34:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579037645; bh=N2S7y+O790zET1Gmtmsm8tuXTXxczW82v07Ij9f4etg=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=E19ztN87s0hx9TSeFhbYpD4KDYFnyV2gto/gqjaKAfYjz7c5aXHcsklLFATfRh40W Krlsmw3JOJcH2iti5LhYFL3x8wnsI4XrND8lAwIc7zpyl15esGA5KHG4rQs7yW5iyD XuiqPr1+p+/FgPX/3BzIPVbdApiWI0BuJYOa6yYg= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 597AF3522755; Tue, 14 Jan 2020 13:34:05 -0800 (PST) Date: Tue, 14 Jan 2020 13:34:05 -0800 From: "Paul E. McKenney" To: Qian Cai Cc: Marco Elver , LKMM Maintainers -- Akira Yokosawa , Alan Stern , Alexander Potapenko , Andrea Parri , Andrey Konovalov , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Boqun Feng , Borislav Petkov , Daniel Axtens , Daniel Lustig , Dave Hansen , David Howells , Dmitry Vyukov , "H. Peter Anvin" , Ingo Molnar , Jade Alglave , Joel Fernandes , Jonathan Corbet , Josh Poimboeuf , Luc Maranget , Mark Rutland , Nicholas Piggin , Peter Zijlstra , Thomas Gleixner , Will Deacon , Eric Dumazet , kasan-dev , linux-arch , "open list:DOCUMENTATION" , linux-efi@vger.kernel.org, Linux Kbuild mailing list , LKML , Linux Memory Management List , the arch/x86 maintainers Subject: Re: [PATCH v4 01/10] kcsan: Add Kernel Concurrency Sanitizer infrastructure Message-ID: <20200114213405.GX2935@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20200114192220.GS2935@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 14, 2020 at 03:30:53PM -0500, Qian Cai wrote: > > > > On Jan 14, 2020, at 2:22 PM, Paul E. McKenney wrote: > > > > Just so I understand... Does this problem happen even in CONFIG_KCSAN=n > > kernels? > > No. Whew!!! ;-) > > I have been running extensive CONFIG_KSCAN=y rcutorture tests for quite > > awhile now, so even if this only happens for CONFIG_KSCAN=y, it is not > > like it affects everyone. > > > > Yes, it should be fixed, and Marco does have a patch on the way. > > The concern is really about setting KSCAN=y in a distro debug kernel where it has other debug options. I’ll try to dig into more of those issues in the next few days. Understood. But there are likely to be other issues with KCSAN, given how new it is. Yes, yes, I certainly would like to believe that the patches we currently know about will make KCSAN perfect for distros, I have way too much grey hair (and too little hair as well!) to really beleive that. As an alternative, once the patches needed for your tests to pass reach mainline, you could announce that KCSAN was ready to be enabled in distros. Though I confess that I don't know how that works. Is there a separate testing kernel binary provided by the distros in question? Thanx, Paul From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH v4 01/10] kcsan: Add Kernel Concurrency Sanitizer infrastructure Date: Tue, 14 Jan 2020 13:34:05 -0800 Message-ID: <20200114213405.GX2935@paulmck-ThinkPad-P72> References: <20200114192220.GS2935@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-doc-owner@vger.kernel.org To: Qian Cai Cc: Marco Elver , LKMM Maintainers -- Akira Yokosawa , Alan Stern , Alexander Potapenko , Andrea Parri , Andrey Konovalov , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Boqun Feng , Borislav Petkov , Daniel Axtens , Daniel Lustig , Dave Hansen , David Howells , Dmitry Vyukov , "H. Peter Anvin" , Ingo Molnar , Jade Alglave , Joel Fernandes List-Id: linux-arch.vger.kernel.org On Tue, Jan 14, 2020 at 03:30:53PM -0500, Qian Cai wrote: > > > > On Jan 14, 2020, at 2:22 PM, Paul E. McKenney wrote: > > > > Just so I understand... Does this problem happen even in CONFIG_KCSAN=n > > kernels? > > No. Whew!!! ;-) > > I have been running extensive CONFIG_KSCAN=y rcutorture tests for quite > > awhile now, so even if this only happens for CONFIG_KSCAN=y, it is not > > like it affects everyone. > > > > Yes, it should be fixed, and Marco does have a patch on the way. > > The concern is really about setting KSCAN=y in a distro debug kernel where it has other debug options. I’ll try to dig into more of those issues in the next few days. Understood. But there are likely to be other issues with KCSAN, given how new it is. Yes, yes, I certainly would like to believe that the patches we currently know about will make KCSAN perfect for distros, I have way too much grey hair (and too little hair as well!) to really beleive that. As an alternative, once the patches needed for your tests to pass reach mainline, you could announce that KCSAN was ready to be enabled in distros. Though I confess that I don't know how that works. Is there a separate testing kernel binary provided by the distros in question? Thanx, Paul