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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 2C107C43382 for ; Fri, 28 Sep 2018 07:01:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D9C2C21746 for ; Fri, 28 Sep 2018 07:01:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="MdHSyCVC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D9C2C21746 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org 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 S1729088AbeI1NXZ (ORCPT ); Fri, 28 Sep 2018 09:23:25 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:33864 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728804AbeI1NXY (ORCPT ); Fri, 28 Sep 2018 09:23:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=0Mc93IaSsturabhMWrsRZ7ic/mZqLn4FrDRgNHfl9yE=; b=MdHSyCVCgr8g0SmU9yqd+LhoH mx72faH7fz6QoteUNnBaGm2vMaf6Xa6vv7WM9e//UkB30Jq6dD/KLkD+O+daijg6PsfTe75OlaEb8 96KS4Ckaro2c41JhG52Zz0mYNvwizbR5msQNNomiLWB6DMzTda1VYRCVDDuNqO2DTI/CTYXC9RVt+ m87W7i5w5JZbyW1mSqyF1ADapIrkIYPsyOyidsFKqrIIeWhJocOYsiD4PiXNWOSmHB71oDG8F+qcg uLXZCuyaR7wXv7IL23s7uygVaPvYp8qvF7UuaqGLHtbTFl6lL4uYKI7tQb8aqTueqtc++uxBEpIlN y8QF1h85w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1g5mlY-0005R9-JP; Fri, 28 Sep 2018 07:00:57 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 445CE21070931; Fri, 28 Sep 2018 09:00:42 +0200 (CEST) Date: Fri, 28 Sep 2018 09:00:42 +0200 From: Peter Zijlstra To: Dmitry Vyukov Cc: syzbot , Ingo Molnar , Will Deacon , LKML , syzkaller-bugs , Thomas Gleixner Subject: Re: BUG: MAX_LOCKDEP_CHAINS too low! Message-ID: <20180928070042.GF3439@hirez.programming.kicks-ass.net> References: <0000000000007523a60576e80a47@google.com> 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 28, 2018 at 08:06:26AM +0200, Dmitry Vyukov wrote: > On Fri, Sep 28, 2018 at 7:51 AM, syzbot > 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.