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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 75FD4C4360F for ; Thu, 4 Apr 2019 16:37:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 42AD3206DF for ; Thu, 4 Apr 2019 16:37:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=maine.edu header.i=@maine.edu header.b="iqYJBAQw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729417AbfDDQhY (ORCPT ); Thu, 4 Apr 2019 12:37:24 -0400 Received: from mail-qt1-f195.google.com ([209.85.160.195]:37735 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728629AbfDDQhX (ORCPT ); Thu, 4 Apr 2019 12:37:23 -0400 Received: by mail-qt1-f195.google.com with SMTP id z16so4011811qtn.4 for ; Thu, 04 Apr 2019 09:37:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=maine.edu; s=google; h=from:date:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=2GPhs65IN3rKza1N9gqevUI9+mfx9z2j/qZ98tDTGR4=; b=iqYJBAQwL6e7qZi6pCEuST7cn0xAIslcwT+FQKf+CGHomxQCFjeQlnIc3ffhzSYcqj LgOb+Ul5z3BBmWgW4ClZXqohxRHljKA+smF/bPMWIrjkUDveVyo6tQBfW4bgpd/6j2b4 FV03DnuUHY/Vu7wQykUfl+AEmrGrvt2qeKCSc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version; bh=2GPhs65IN3rKza1N9gqevUI9+mfx9z2j/qZ98tDTGR4=; b=UfQNTvkf/v1G94iRrl8uK2z2Dvuj5EQKe6EP+JBdKvnrj04FJMu2gWfqjxV9BRK0hs /QZ8O8VXtYJlke+aPGLUX9bxcwQ+//qcPp51gCJ1mH8b1CAnb5eUn3qLvabD7R9D2jZz 39lGC+kz+pPvfW5XLoJXtYDPoZgWdapV2FsWiYPFTXuFAJZo6tYTfSpXrPwXVsA8JLMp Akr4r79Ez2gjqTV1mgJ89KVA1e1i3Vk09Z78M9hi2Q0NO7mkpGW+MW6NW31meSoZ7iv7 DUzEWgM/zVyeq4GFHvwtFNY+Gyo+Pe69xCII+7eQksFQ1s3vWEcYpNl48QSwYyX79ua1 AaWQ== X-Gm-Message-State: APjAAAU446Mv4e4mDbXBZa7owV902bbFDjOLiDKpzfywJqXN4vLJxMR2 1cklDnoItOjkpprhHDeZ9mPYSA== X-Google-Smtp-Source: APXvYqxsHU0bdIOxr9A03Au/YIPYDhJW634Y4WEKvfpErqW42IwlqvIF0k1aooOWXJLM7rsyYyFGqg== X-Received: by 2002:ac8:380f:: with SMTP id q15mr6402524qtb.163.1554395842996; Thu, 04 Apr 2019 09:37:22 -0700 (PDT) Received: from macbook-air (weaver.eece.maine.edu. [130.111.218.23]) by smtp.gmail.com with ESMTPSA id 56sm12359599qto.57.2019.04.04.09.37.21 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 04 Apr 2019 09:37:22 -0700 (PDT) From: Vince Weaver X-Google-Original-From: Vince Weaver Date: Thu, 4 Apr 2019 12:37:18 -0400 (EDT) X-X-Sender: vince@macbook-air To: Cyrill Gorcunov cc: Vince Weaver , Peter Zijlstra , linux-kernel@vger.kernel.org, Arnaldo Carvalho de Melo , Alexander Shishkin , Ingo Molnar , Borislav Petkov , Namhyung Kim , Thomas Gleixner , Jiri Olsa , Stephane Eranian Subject: Re: perf: perf_fuzzer crashes on Pentium 4 systems In-Reply-To: <20190404133327.GP1421@uranus.lan> Message-ID: References: <20190403191944.GH1421@uranus.lan> <20190403203144.GI1421@uranus.lan> <20190404133327.GP1421@uranus.lan> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 4 Apr 2019, Cyrill Gorcunov wrote: > On Thu, Apr 04, 2019 at 09:25:47AM -0400, Vince Weaver wrote: > > > > It looks like there are at least two bugs here, one that's a full > > hardlockup with nothing on serial console. The other is the NULL > > dereference. OK, it turns out the hard-lock and the null pointer dereference might be the same, I have a random seed for the fuzzer from a hard-lock crash that reproduces and it generated the null pointer crash. (This is with your patch applied). I can try to see if I can bisect down to a specific event sequence that triggers this, but that can be tricky sometimes if things lock up so fast that the event log doesn't get written out before the crash. Vince