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=-7.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,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 54A79C352AA for ; Tue, 1 Oct 2019 21:19:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 26E8E2168B for ; Tue, 1 Oct 2019 21:19:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="xEclNzVy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727762AbfJAVTv (ORCPT ); Tue, 1 Oct 2019 17:19:51 -0400 Received: from mail-pg1-f193.google.com ([209.85.215.193]:43853 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727764AbfJAVTv (ORCPT ); Tue, 1 Oct 2019 17:19:51 -0400 Received: by mail-pg1-f193.google.com with SMTP id v27so10565186pgk.10 for ; Tue, 01 Oct 2019 14:19:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=INoMgnqhH49ZFKFHhyaP4EdT7D9OjFM4A6O+XvHM0Oo=; b=xEclNzVyc/D7N5Pge7bXfLSjXeQWU6dKIYmcYVwA0mJBEwv3nJRePW7ixJ+OxOcEf3 oF8fbGpU8WMh5ENrdibkuN3eJ4d/6QL8kHv+ljNO/Ezfnx9lH6BigkMrQZIU522JciH7 u0AD7f3sMRmvaHpFNXgr6Ke+8I6D7d3q6Ea5o= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=INoMgnqhH49ZFKFHhyaP4EdT7D9OjFM4A6O+XvHM0Oo=; b=WiEHwkoDyo4XlwJwtKj0imDV80szOob+McjmXATLwqRWGVmR1KHP5+rI8B5L1HffP3 xGJk5MRAX89vcZT9EAlT0SQ9cpwrq3yY/S/+vuMF3ME/HNygA8cS+15ggfPOFsUtF8a/ wAjElhbALdGSXYZamFkx0Y6IkckZHKgHJXVlSrUniEu5jc9vow7M4SuWY2sjL1o5vaIT vu3epfH86oc/dTzGcZD9t8baOnzjn7c8CYKea1V5W7F58+GWeF9gpWnvlq0oF5vGGceM FrzoS/17tjB+Q6iPv9VfslVJTGckxRYgJtp9tPvJUUmn3ffiiigkUjQxkJcq/+1/iBDd NBwQ== X-Gm-Message-State: APjAAAXD+4bYoWzLpYSk+Ifp6cNGMqgLxc04IOvAofTjQPmqUWy5NiWH Emv6RpOISb3Yj1O2V3CpNiQktg== X-Google-Smtp-Source: APXvYqykfKxPl+xURQAGrxObt96rfgwmrAvdzsBTTtUGsm71bavcOXuDxOhHS9rP8Fe8Jas2SKCfWA== X-Received: by 2002:a17:90a:21a9:: with SMTP id q38mr239494pjc.23.1569964790305; Tue, 01 Oct 2019 14:19:50 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id e3sm3080069pjs.15.2019.10.01.14.19.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Oct 2019 14:19:49 -0700 (PDT) Date: Tue, 1 Oct 2019 17:19:48 -0400 From: Joel Fernandes To: Marco Elver Cc: kasan-dev , LKML , Dmitry Vyukov , Andrey Konovalov , Alexander Potapenko , paulmck@linux.ibm.com, Paul Turner , Daniel Axtens , Anatol Pomazau , Will Deacon , Andrea Parri , stern@rowland.harvard.edu, akiyks@gmail.com, npiggin@gmail.com, boqun.feng@gmail.com, dlustig@nvidia.com, j.alglave@ucl.ac.uk, luc.maranget@inria.fr Subject: Re: Kernel Concurrency Sanitizer (KCSAN) Message-ID: <20191001211948.GA42035@google.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 20, 2019 at 04:18:57PM +0200, Marco Elver wrote: > Hi all, > > We would like to share a new data-race detector for the Linux kernel: > Kernel Concurrency Sanitizer (KCSAN) -- > https://github.com/google/ktsan/wiki/KCSAN (Details: > https://github.com/google/ktsan/blob/kcsan/Documentation/dev-tools/kcsan.rst) > > To those of you who we mentioned at LPC that we're working on a > watchpoint-based KTSAN inspired by DataCollider [1], this is it (we > renamed it to KCSAN to avoid confusion with KTSAN). > [1] http://usenix.org/legacy/events/osdi10/tech/full_papers/Erickson.pdf > > In the coming weeks we're planning to: > * Set up a syzkaller instance. > * Share the dashboard so that you can see the races that are found. > * Attempt to send fixes for some races upstream (if you find that the > kcsan-with-fixes branch contains an important fix, please feel free to > point it out and we'll prioritize that). > > There are a few open questions: > * The big one: most of the reported races are due to unmarked > accesses; prioritization or pruning of races to focus initial efforts > to fix races might be required. Comments on how best to proceed are > welcome. We're aware that these are issues that have recently received > attention in the context of the LKMM > (https://lwn.net/Articles/793253/). > * How/when to upstream KCSAN? Looks exciting. I think based on our discussion at LPC, you mentioned one way of pruning is if the compiler generated different code with _ONCE annotations than what would have otherwise been generated. Is that still on the table, for the purposing of pruning the reports? Also appreciate a CC on future patches as well. thanks, - Joel > > Feel free to test and send feedback. > > Thanks, > -- Marco