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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 0FC6FC433DF for ; Wed, 13 May 2020 16:25:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 538922064E for ; Wed, 13 May 2020 16:25:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389578AbgEMQZ1 (ORCPT ); Wed, 13 May 2020 12:25:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:42932 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730831AbgEMQZ0 (ORCPT ); Wed, 13 May 2020 12:25:26 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6FB972064E; Wed, 13 May 2020 16:25:26 +0000 (UTC) Date: Wed, 13 May 2020 12:25:24 -0400 From: Steven Rostedt To: Sven Schnelle Cc: LKML , lkp@lists.01.org Subject: Re: [tracing] 06e0a548ba: WARNING:at_kernel/trace/ring_buffer.c:#ring_buffer_iter_peek Message-ID: <20200513122524.2352c105@gandalf.local.home> In-Reply-To: <20200513161557.GA73453@tuxmaker.boeblingen.de.ibm.com> References: <20200429090508.GG5770@shao2-debian> <20200513091906.GA12720@tuxmaker.boeblingen.de.ibm.com> <20200513092922.6d79f6ee@gandalf.local.home> <20200513161557.GA73453@tuxmaker.boeblingen.de.ibm.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 13 May 2020 18:15:57 +0200 Sven Schnelle wrote: > Thanks for looking into this. I've attached my /proc/config.gz to this Mail. > The x86 system is my Laptop which is a Thinkpad X280 with 4 HT CPUs (so 8 cpus > in total). I've tried disabling preemption, but this didn't help. > > It's always this check that causes the loop: > > if (iter->head >= rb_page_size(iter->head_page)) { > rb_inc_iter(iter); > goto again; > } > > On the first loop iter->head is some value > 0 and rb_page_size returns > 0, afterwards it gets twice to this check with both values 0. The third > time the warning is triggered. Maybe that information helps. Letting it run long enough, I was able to trigger it. I think I know what's wrong with it. I'll put in some debugging to see if my thoughts are accurate. Thanks for bringing this back to my attention. -- Steve From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============5275899255155291539==" MIME-Version: 1.0 From: Steven Rostedt To: lkp@lists.01.org Subject: Re: [tracing] 06e0a548ba: WARNING:at_kernel/trace/ring_buffer.c:#ring_buffer_iter_peek Date: Wed, 13 May 2020 12:25:24 -0400 Message-ID: <20200513122524.2352c105@gandalf.local.home> In-Reply-To: <20200513161557.GA73453@tuxmaker.boeblingen.de.ibm.com> List-Id: --===============5275899255155291539== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On Wed, 13 May 2020 18:15:57 +0200 Sven Schnelle wrote: > Thanks for looking into this. I've attached my /proc/config.gz to this Ma= il. > The x86 system is my Laptop which is a Thinkpad X280 with 4 HT CPUs (so 8= cpus > in total). I've tried disabling preemption, but this didn't help. > = > It's always this check that causes the loop: > = > if (iter->head >=3D rb_page_size(iter->head_page)) { > rb_inc_iter(iter); > goto again; > } > = > On the first loop iter->head is some value > 0 and rb_page_size returns > 0, afterwards it gets twice to this check with both values 0. The third > time the warning is triggered. Maybe that information helps. Letting it run long enough, I was able to trigger it. I think I know what's wrong with it. I'll put in some debugging to see if my thoughts are accurate. Thanks for bringing this back to my attention. -- Steve --===============5275899255155291539==--