From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-13.3 required=5.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_NONE, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id BCF667D90F for ; Fri, 15 Nov 2019 12:02:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727362AbfKOMCW (ORCPT ); Fri, 15 Nov 2019 07:02:22 -0500 Received: from mail-oi1-f194.google.com ([209.85.167.194]:40352 "EHLO mail-oi1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727215AbfKOMCW (ORCPT ); Fri, 15 Nov 2019 07:02:22 -0500 Received: by mail-oi1-f194.google.com with SMTP id d22so1450255oic.7 for ; Fri, 15 Nov 2019 04:02:21 -0800 (PST) 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=RRytg93FU7f6sfBrcqBa/NI8/4Q9Vec4eDf1e8YsiLA=; b=nVJwYDJCtXWgpUbdQGvyEnuFLUcgdoMeKxiPthFRXCdtZdTeFIDBqKZ6+bNhKMXARK FiuRwf09ZIePoP7o/Ki7Hfnl+pJjquU+FvzRQG4URKaKiWDYzrj+CImuhHJEJ2NcFIIn mpboR/iTkoBaC8CDx8OxDvhdd72HtlFQl9ugHgGSp3pFy8Jdcdj3EjJAV3NcXjs4jBGG HcWRqotcj1x+8mz1un8uwKWvI1p5uNiUwHjldbs8fjcRCwN5wBTM7BvtzXYUp0JF//Dd 7I+pJyMn6PlWTucSGO3aGtxcpZVvuzFq6Q9pu+lqZ+6Jy9GBjB21YirKDhsibmAdtSdW QtPw== 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=RRytg93FU7f6sfBrcqBa/NI8/4Q9Vec4eDf1e8YsiLA=; b=dx5rlazOSlTfRU4/6iS6gbmOp4PZSU5N1PvHByFamiznUIl++lno01WClcVD4R0rJ4 SVMVqROIImzSBWg+57zyKtdRZ0vGHIIEx37zt3D24lnn0EwxIO4uqWIvRr9HIgk7w9sy plOPuNVoctLXT6waR5/OTZuR8q2mP8j3RtJCVy5u79R8BJncywPZ6srSj61SaI4obvXq Yu5gCnakButNYgN/WZoqGd9nakWYl7JZW0Xo/b1d6s/EOrjV3t2cnXSYILqmbUK9adP8 fW/+xbUqKw9BfEPo7WA+GvxaFbFz18JmW0wwfPUcl/9NLtBSlSiZ8Q7bk6GOVCfBTckz OIWQ== X-Gm-Message-State: APjAAAUZ1yC8kSJiBeH3SBlYLpvNo4RV+oXbNyPhlEB28W/5aO7TUb5X KANGBGzDBPFbqGGITdpJLK9ZoVls77vbDkg4GeNyEQ== X-Google-Smtp-Source: APXvYqx6zqcXYMp7eFJA/krQ5decJuNJdJO30uNxuNlyEY/pcLWFYr8pgT33say7KL4tYPQxYL+H1c4MsqJbhx+1xvc= X-Received: by 2002:aca:5413:: with SMTP id i19mr7842386oib.121.1573819340279; Fri, 15 Nov 2019 04:02:20 -0800 (PST) MIME-Version: 1.0 References: <20191114180303.66955-1-elver@google.com> <20191114195046.GP2865@paulmck-ThinkPad-P72> <20191114213303.GA237245@google.com> <20191114221559.GS2865@paulmck-ThinkPad-P72> In-Reply-To: <20191114221559.GS2865@paulmck-ThinkPad-P72> From: Marco Elver Date: Fri, 15 Nov 2019 13:02:08 +0100 Message-ID: Subject: Re: [PATCH v4 00/10] Add Kernel Concurrency Sanitizer (KCSAN) To: "Paul E. McKenney" Cc: 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" Content-Type: text/plain; charset="UTF-8" Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu, 14 Nov 2019 at 23:16, Paul E. McKenney wrote: > > On Thu, Nov 14, 2019 at 10:33:03PM +0100, Marco Elver wrote: > > On Thu, 14 Nov 2019, Paul E. McKenney wrote: > > > > > On Thu, Nov 14, 2019 at 07:02:53PM +0100, Marco Elver wrote: > > > > This is the patch-series for the Kernel Concurrency Sanitizer (KCSAN). > > > > KCSAN is a sampling watchpoint-based *data race detector*. More details > > > > are included in **Documentation/dev-tools/kcsan.rst**. This patch-series > > > > only enables KCSAN for x86, but we expect adding support for other > > > > architectures is relatively straightforward (we are aware of > > > > experimental ARM64 and POWER support). > > > > > > > > To gather early feedback, we announced KCSAN back in September, and have > > > > integrated the feedback where possible: > > > > http://lkml.kernel.org/r/CANpmjNPJ_bHjfLZCAPV23AXFfiPiyXXqqu72n6TgWzb2Gnu1eA@mail.gmail.com > > > > > > > > The current list of known upstream fixes for data races found by KCSAN > > > > can be found here: > > > > https://github.com/google/ktsan/wiki/KCSAN#upstream-fixes-of-data-races-found-by-kcsan > > > > > > > > We want to point out and acknowledge the work surrounding the LKMM, > > > > including several articles that motivate why data races are dangerous > > > > [1, 2], justifying a data race detector such as KCSAN. > > > > > > > > [1] https://lwn.net/Articles/793253/ > > > > [2] https://lwn.net/Articles/799218/ > > > > > > I queued this and ran a quick rcutorture on it, which completed > > > successfully with quite a few reports. > > > > Great. Many thanks for queuing this in -rcu. And regarding merge window > > you mentioned, we're fine with your assumption to targeting the next > > (v5.6) merge window. > > > > I've just had a look at linux-next to check what a future rebase > > requires: > > > > - There is a change in lib/Kconfig.debug and moving KCSAN to the > > "Generic Kernel Debugging Instruments" section seems appropriate. > > - bitops-instrumented.h was removed and split into 3 files, and needs > > re-inserting the instrumentation into the right places. > > > > Otherwise there are no issues. Let me know what you recommend. > > Sounds good! > > I will be rebasing onto v5.5-rc1 shortly after it comes out. My usual > approach is to fix any conflicts during that rebasing operation. > Does that make sense, or would you prefer to send me a rebased stack at > that point? Either way is fine for me. That's fine with me, thanks! To avoid too much additional churn on your end, I just replied to the bitops patch with a version that will apply with the change to bitops-instrumented infrastructure. Also considering the merge window, we had a discussion and there are some arguments for targeting the v5.5 merge window: - we'd unblock ARM and POWER ports; - we'd unblock people wanting to use the data_race macro; - we'd unblock syzbot just tracking upstream; Unless there are strong reasons to not target v5.5, I leave it to you if you think it's appropriate. Thanks, -- Marco