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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,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 91B6DC04EB8 for ; Thu, 6 Dec 2018 15:44:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5EE86214C1 for ; Thu, 6 Dec 2018 15:44:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5EE86214C1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.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 S1726045AbeLFPo3 (ORCPT ); Thu, 6 Dec 2018 10:44:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:19576 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725849AbeLFPo2 (ORCPT ); Thu, 6 Dec 2018 10:44:28 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 75A6C30DDBC5; Thu, 6 Dec 2018 15:44:28 +0000 (UTC) Received: from krava (unknown [10.43.17.30]) by smtp.corp.redhat.com (Postfix) with SMTP id 6BAF56C1FC; Thu, 6 Dec 2018 15:44:26 +0000 (UTC) Date: Thu, 6 Dec 2018 16:44:25 +0100 From: Jiri Olsa To: Vince Weaver Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Namhyung Kim , Andi Kleen Subject: Re: perf: perf_fuzzer triggers GPF in perf_prepare_sample Message-ID: <20181206154425.GA21381@krava> References: <20181205124538.GA19343@krava> <20181205163838.GA3836@krava> <20181205183326.GE3836@krava> 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) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Thu, 06 Dec 2018 15:44:28 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 06, 2018 at 10:35:28AM -0500, Vince Weaver wrote: > On Wed, 5 Dec 2018, Jiri Olsa wrote: > > > On Wed, Dec 05, 2018 at 12:11:19PM -0500, Vince Weaver wrote: > > > On Wed, 5 Dec 2018, Jiri Olsa wrote: > > > > > > > On Wed, Dec 05, 2018 at 01:45:38PM +0100, Jiri Olsa wrote: > > > > > On Tue, Dec 04, 2018 at 10:54:55AM -0500, Vince Weaver wrote: > > > > > > Hello, > > > > > > > > > > > > I was able to trigger another oops with the perf_fuzzer with current git. > > > > > > > > > > > > This is 4.20-rc5 after the fix for the very similar oops I previously > > > > > > reported got committed. > > > > > > > > > > > > It seems to be pointing to the same location in the source as > > > > > > before, I guess maybe triggered a different way? > > > > > > > > > > nice.. yep, looks the same > > > > > > > > > > > > > > > > > Unfortunately this crash is not easily reproducible like the last one was. > > > > > > > > > > will check > > > > > > > > what model are hitting this on? > > > > > > Haswell. 6/60/3. > > > > > > While I can't deterministically trigger this, the fuzzer usually hits it > > > within an hour or two. Is there any debug or printk messages I can > > > add that would help figure out what's going on? > > > > I can't see how we could end up with that config other than > > some corruption.. the only way I see could be that we touch > > cpu->events array without checking its active_mask bit > > > > but that does not explain why the crash happened in the same > > place as before > > Maybe it is a corruption issue. I had applied my own debug patch that > would dump some info if data->callchain was NULL. > > But my debug code didn't trigger this time because it looks like > data->callchain was "1" rather than "0". > > [27764.840179] BUG: unable to handle kernel NULL pointer dereference at 0000000000000001 > [27764.840179] PGD 0 P4D 0 > [27764.840180] Oops: 0000 [#1] SMP PTI > [27764.840180] CPU: 1 PID: 18687 Comm: perf_fuzzer Tainted: G W 4.20.0-rc5+ #125 > [27764.840180] Hardware name: LENOVO 10AM000AUS/SHARKBAY, BIOS FBKT72AUS 01/26/2014 actually, you could try that patch from my previous email? thanks, jirka