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=-14.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL 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 842F6C43461 for ; Wed, 16 Sep 2020 19:08:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2D39C206DB for ; Wed, 16 Sep 2020 19:08:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="LbcnFSLB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728154AbgIPTHx (ORCPT ); Wed, 16 Sep 2020 15:07:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727295AbgIPRoz (ORCPT ); Wed, 16 Sep 2020 13:44:55 -0400 Received: from mail-qv1-xf42.google.com (mail-qv1-xf42.google.com [IPv6:2607:f8b0:4864:20::f42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 789B2C0698CB for ; Wed, 16 Sep 2020 04:28:34 -0700 (PDT) Received: by mail-qv1-xf42.google.com with SMTP id b13so3319460qvl.2 for ; Wed, 16 Sep 2020 04:28:34 -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=rnKcSlNkQR35LZf6iND6zHQpJOWDy/dSu0BrUtUSzkE=; b=LbcnFSLBii35TjI4Hw5pPUs1/st3gHYC+ASBPFwHWMKMpNzK2VB2UixcZ/j9kJRgSO k/xy69mEwCXzw3XZeqk8eX47sZ3+aZ8shmj6m1AGrUbViI8jmB1Md9rRtUcrudBLJe6j retA+MwIvQa2N7Hj4kUyxSibd7QVqw8ptlyKIBw8yoOaSLBRSjisGs7QwajJHnqV9Nhk 9PT87+aV1o5dVkn+/J6yffrnFkyvLchUprUGWWAFAEQsSwHA0ldI3r+b2LBb40yKa/iO zoT5OnR1OqrfwEMGJTdBQJEauDuudHtB7jS+F7gbztZ6D3rHEu23lAXKQP8HX8BFwpc+ UGuQ== 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=rnKcSlNkQR35LZf6iND6zHQpJOWDy/dSu0BrUtUSzkE=; b=mwo9rO1gBvC6RITSjKsgFq5maEj5qVkAVViKGt77kVqeNlzxqNIv76vJA/0JUrdki9 VhY8N8Q/1FERx/uGJ0vBuPyBlxMGZWKahZvLf7/TNn5iBZB0xzW+rVqQreTi4W/vTDof naDROjKznjtXhiF0pg+a5epoRJdCDiCWMyAfVUYSISiwHsEgP7rQcjpRDxuOPL/jWOMy e8YbHBly4uIkX1nzFvBzj1Tjf1hqmEg94T4VO/UkbnFjr/gxGqa7Nr5MDgRSs4sMf/D5 rZvoDsttVj1By04NOsbbZ0HfwNRsRzxG5Q2bFz2dRaZ1G+MiD9lP2OXnIEXVez0iHGGI 9syQ== X-Gm-Message-State: AOAM532cKRdc3njrby1NFL9gwvXOGvYbLFJ8KRW6E/rVBDSfWXWFvfi5 rvTQzrUXFWkZfI0VIdvMU4elzniMRaX8MqlgjtOTUA== X-Google-Smtp-Source: ABdhPJzV6FkEuZbmAv7oARvd/eh2RnB+dgMffb2TR9yN0gIClEXp5egnd6G5hCJ9qchy7RbOzo6GZmxnYvrPUwb2qFU= X-Received: by 2002:ad4:4e33:: with SMTP id dm19mr6414279qvb.47.1600255711033; Wed, 16 Sep 2020 04:28:31 -0700 (PDT) MIME-Version: 1.0 References: <1595640639-9310-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> <384ce711-25c5-553b-8d22-965847132fbd@i-love.sakura.ne.jp> <0f7233f7-a04a-e9c9-7920-3a170cc97e4b@i-love.sakura.ne.jp> In-Reply-To: <0f7233f7-a04a-e9c9-7920-3a170cc97e4b@i-love.sakura.ne.jp> From: Dmitry Vyukov Date: Wed, 16 Sep 2020 13:28:19 +0200 Message-ID: Subject: Re: [PATCH v2] lockdep: Allow tuning tracing capacity constants. To: Tetsuo Handa Cc: Peter Zijlstra , Ingo Molnar , Will Deacon , Andrew Morton , LKML , syzkaller 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 Fri, Sep 4, 2020 at 6:05 PM Tetsuo Handa wrote: > > Hello. Can we apply this patch? > > This patch addresses top crashers for syzbot, and applying this patch > will help utilizing syzbot's resource for finding other bugs. Acked-by: Dmitry Vyukov Peter, do you still have concerns with this? Both MAX_LOCKDEP_ENTRIES and MAX_LOCKDEP_CHAINS still fire on syzbot a lot and harm ability to test whole kernel: https://syzkaller.appspot.com/bug?id=3d97ba93fb3566000c1c59691ea427370d33ea1b https://syzkaller.appspot.com/bug?id=63fc8d0501c39609dd2f268e4190ec9a72619563 I hate disabling lockdep entirely as it also finds lots of useful things. > On 2020/08/28 0:20, Tetsuo Handa wrote: > > Since syzkaller continues various test cases until the kernel crashes, > > syzkaller tends to examine more locking dependencies than normal systems. > > As a result, syzbot is reporting that the fuzz testing was terminated > > due to hitting upper limits lockdep can track [1] [2] [3]. > > > > Let's allow individually tuning upper limits via kernel config options > > (based on an assumption that there is no inter-dependency among these > > constants). > > > > [1] https://syzkaller.appspot.com/bug?id=3d97ba93fb3566000c1c59691ea427370d33ea1b > > [2] https://syzkaller.appspot.com/bug?id=381cb436fe60dc03d7fd2a092b46d7f09542a72a > > [3] https://syzkaller.appspot.com/bug?id=a588183ac34c1437fc0785e8f220e88282e5a29f > > > > Reported-by: syzbot > > Reported-by: syzbot > > Reported-by: syzbot > > Signed-off-by: Tetsuo Handa > > --- > > kernel/locking/lockdep.c | 2 +- > > kernel/locking/lockdep_internals.h | 8 +++--- > > lib/Kconfig.debug | 40 ++++++++++++++++++++++++++++++ > > 3 files changed, 45 insertions(+), 5 deletions(-) > >