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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 B5FAAC43331 for ; Mon, 11 Nov 2019 19:01:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8FAA8222BD for ; Mon, 11 Nov 2019 19:01:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573498915; bh=2FW1doQBV2NX9sicCfo3h+ExRWGyhemW59yfH0imPVo=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=Q25s0YRzz24LBXhADBWuiP2q/R50z50tuucDAR8jO62xdA+SSxke0CVR7ITy1cI2q 6jhIo7Yqm74K8aNkZ3vUYRvBdptrChLNP6lLQAC+9FEVYBCjlGJRhuwepssq6mw2ME SzzEDWuazv7Tz5ZPIGIj9Iy3J40gu/HRfE9POgAA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730395AbfKKTBy (ORCPT ); Mon, 11 Nov 2019 14:01:54 -0500 Received: from mail-lj1-f193.google.com ([209.85.208.193]:36416 "EHLO mail-lj1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729338AbfKKSum (ORCPT ); Mon, 11 Nov 2019 13:50:42 -0500 Received: by mail-lj1-f193.google.com with SMTP id k15so14972363lja.3 for ; Mon, 11 Nov 2019 10:50:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=tzwj0Bcu0+gyIzlUlN7XJHfbOaRzWPHagplExJJIvPs=; b=ew5m8ZL/3PZXEH82FW7NciyTpX79pXMZzxowB+MlMPaTW/kiutG2GumvXkfpUaRgOq P2W1GftekPzYO7cncT0B3PbtH2mr6stdJFhMeleFIDj20NSRAHa/lpsPd2tHpgwHBNki C9b4sV+Ddh67bYfuCFNneVQaMCjOafWrdcZl4= 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=tzwj0Bcu0+gyIzlUlN7XJHfbOaRzWPHagplExJJIvPs=; b=atJmU9Igr+lGVogFj/mLfrXWCDejevlTESkLd6v5D62btodHIdn53DJmYnh8y/K+RF hYzaxofY/WU5gWJJwnbLUG++R93nRx2maCGT+T+SSarFpWeVHSBacgu035JSweCfabHX zmo3Xil9P73UMlLx5GBpbvx0NgC482Tlt5qojvKkhl3b//PXn4pMMp9YmSzAmZ5DJwJu Xr/0Qd5lgxHq4vlV6SFwRvDEVNi1lpJVj3zaMOxjyZb2OZfKHMcPp64x9j95dauG2uQj d1VAqAle0fJT9jm2lytlsovWxFOObIonWxcUiZ2b5qNs74F+MtZqLqsvyvi/A8UCR2SY 4J+g== X-Gm-Message-State: APjAAAUWl0sZzwmzMb9L4Qqxa70SwfVkO6pCJZPpQrhE8dUSxKRmZBtB 1wrv2p+jC2boQzAT5PDh/7zzUNzwN6E= X-Google-Smtp-Source: APXvYqxgnjQlnUBf2y4y+UqZYWyjA3YHZzywxlbc3RmgPNtSO5Jy8A4kUpJC8N1c62zT3D1xwi5Brg== X-Received: by 2002:a2e:8601:: with SMTP id a1mr17604295lji.159.1573498240124; Mon, 11 Nov 2019 10:50:40 -0800 (PST) Received: from mail-lf1-f49.google.com (mail-lf1-f49.google.com. [209.85.167.49]) by smtp.gmail.com with ESMTPSA id z24sm8026839lfj.40.2019.11.11.10.50.38 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Nov 2019 10:50:39 -0800 (PST) Received: by mail-lf1-f49.google.com with SMTP id q5so4669385lfo.10 for ; Mon, 11 Nov 2019 10:50:38 -0800 (PST) X-Received: by 2002:a19:c790:: with SMTP id x138mr16826204lff.61.1573498238697; Mon, 11 Nov 2019 10:50:38 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Linus Torvalds Date: Mon, 11 Nov 2019 10:50:22 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: KCSAN: data-race in __alloc_file / __alloc_file To: Eric Dumazet Cc: Alan Stern , Marco Elver , Eric Dumazet , syzbot , linux-fsdevel , Linux Kernel Mailing List , syzkaller-bugs , Al Viro , Andrea Parri , "Paul E. McKenney" , LKMM Maintainers -- Akira Yokosawa 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, Nov 11, 2019 at 10:31 AM Eric Dumazet wrote: > > Problem is that KASAN/KCSAN stops as soon as one issue is hit, > regardless of it being a false positive or not. So mayb e that - together with the known huge base of false positives - just means that KCSAN needs some more work before it can be used as a basis for sending out patches. Maybe the reporting needs to create a hash of the location, and report once per location? Or something like that. Maybe KCSAN needs a way to filter out known false positives on a KCSAN side, without having to change the source for a tool that gives too much noise? > If we do not annotate the false positive, the real issues might be > hidden for years. I don't think "change the kernel source for a tool that isn't good enough" is the solution. > There is no pattern really, only a lot of noise (small ' bugs' that > have no real impact) Yeah, if it hasn't shown any real bugs so far, that just strengthens the "it needs much fewer false positives to be useful". KASAN and lockdep can afford to stop after the first problem, because the problems they report - and the additional annotations you might want to add - are quality problems and annotations. Linus