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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 0D97FC43382 for ; Fri, 28 Sep 2018 07:56:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3079216FE for ; Fri, 28 Sep 2018 07:56:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Q5hNOrnE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B3079216FE Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729068AbeI1OTO (ORCPT ); Fri, 28 Sep 2018 10:19:14 -0400 Received: from mail-it1-f196.google.com ([209.85.166.196]:50760 "EHLO mail-it1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728804AbeI1OTO (ORCPT ); Fri, 28 Sep 2018 10:19:14 -0400 Received: by mail-it1-f196.google.com with SMTP id j81-v6so1588770ite.0 for ; Fri, 28 Sep 2018 00:56:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=HWpsdd2Fka1HgGR3nWvg3f1+1jEYCBt7S6Rp6t1rgWo=; b=Q5hNOrnEuqR8WClhtxeSAOXX4ERBqtRCGgy+1udIcVj7KfGjjjsyN03g2aAOzjn+5X 1jo55Kka0BKNVAftyzpvi+gHGZ2SHSq3hq8dk7pVfzAadl2uzQGXGWPaTE+CV0Dn4sfW /lKM0O9EAbNARKAraOM5eCxCvdZAQWiePVmvqROqnxh+IiCiZjOsVHx+A515SsBFfucf PYSLr2jrOakdRcUi6TxW5WFHGL6lYM2tc64vUtqPs4iOLm1m6uVMB/l2cTYOIh0oN/da hOdv65oSshKoKO7FAQ/dXWs/tPSMwOeJmDhV3chQEW/CoWyogty/Ejg6/OcmZs81jDxN HG5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=HWpsdd2Fka1HgGR3nWvg3f1+1jEYCBt7S6Rp6t1rgWo=; b=aQH7lHUpVdA7YXqQus7GvObrXTB3hSDfK5iNfF2uMFbMpb8txLhuNojg8F6V8wmxGa IKaVltV8G24YdsS+SD+Fj/AG5x0zMrD7IslzPH/IIpwr4NzLte9DwUIgVJDqMioHf5ek ql44xsqqy/3oygcUAh5w5vGp26Y8uOvcUhT46f9YF3tkxN0DGjsX/CFEJ+0DnVNiurP/ xc7QuDj0lDniZt/8YVykkcfWWQt/Htx8a2FogSywOvVTNy4Vg9+VqgtOiepmc31Sj88l uTc/av7uMUB40619U8scC92Uxf2Zs8yO/WjmwkEs/h0jqobRB+RaqZHflVJ/1jym7Z5/ 6Mdg== X-Gm-Message-State: ABuFfohbwihcWapchLkJNhR1H+ilraRD1PmeDdCzFyAQwyFZwab3S0P1 ZWmIXaYIQ56Xfww94/22pBTJMhFO1m7Szmk3oOiSxw== X-Google-Smtp-Source: ACcGV61Bbp/H582NR5c9JZmA33h1yxw4eIbSK4oc54jRV5ZiVaepVE02s8tXnzcXhmf8Koszcki3YYUx/IMhlktnMbI= X-Received: by 2002:a24:3383:: with SMTP id k125-v6mr734646itk.14.1538121404508; Fri, 28 Sep 2018 00:56:44 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a02:ab8c:0:0:0:0:0 with HTTP; Fri, 28 Sep 2018 00:56:23 -0700 (PDT) In-Reply-To: <20180928070042.GF3439@hirez.programming.kicks-ass.net> References: <0000000000007523a60576e80a47@google.com> <20180928070042.GF3439@hirez.programming.kicks-ass.net> From: Dmitry Vyukov Date: Fri, 28 Sep 2018 09:56:23 +0200 Message-ID: Subject: Re: BUG: MAX_LOCKDEP_CHAINS too low! To: Peter Zijlstra Cc: syzbot , Ingo Molnar , Will Deacon , LKML , syzkaller-bugs , Thomas Gleixner 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 28, 2018 at 9:00 AM, Peter Zijlstra wrote: >> > Hello, >> > >> > syzbot found the following crash on: >> > >> > HEAD commit: c307aaf3eb47 Merge tag 'iommu-fixes-v4.19-rc5' of git://gi.. >> > git tree: upstream >> > console output: https://syzkaller.appspot.com/x/log.txt?x=13810df1400000 >> > kernel config: https://syzkaller.appspot.com/x/.config?x=dfb440e26f0a6f6f >> > dashboard link: https://syzkaller.appspot.com/bug?extid=aaa6fa4949cc5d9b7b25 >> > compiler: gcc (GCC) 8.0.1 20180413 (experimental) >> > >> > Unfortunately, I don't have any reproducer for this crash yet. >> > >> > IMPORTANT: if you fix the bug, please add the following tag to the commit: >> > Reported-by: syzbot+aaa6fa4949cc5d9b7b25@syzkaller.appspotmail.com >> >> +LOCKDEP maintainers, >> >> What does this BUG mean? And how should it be fixed? >> >> Thanks >> >> > BUG: MAX_LOCKDEP_CHAINS too low! > > Is the his result of endlessly loading and unloading modules? > > In which case, the fix is: don't do that then. No modules involved, we don't have any modules in the image. Must be something else. Perhaps syzkaller just produced a workload so diverse that nobody ever produced.