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_1 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 3A863C7618B for ; Thu, 25 Jul 2019 15:50:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0EC3622BF5 for ; Thu, 25 Jul 2019 15:50:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389487AbfGYPuz (ORCPT ); Thu, 25 Jul 2019 11:50:55 -0400 Received: from ale.deltatee.com ([207.54.116.67]:37956 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389566AbfGYPuz (ORCPT ); Thu, 25 Jul 2019 11:50:55 -0400 Received: from s01061831bf6ec98c.cg.shawcable.net ([68.147.80.180] helo=[192.168.6.132]) by ale.deltatee.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1hqg17-0007t9-3O; Thu, 25 Jul 2019 09:50:54 -0600 To: Nicholas Johnson , Bjorn Helgaas Cc: Benjamin Herrenschmidt , Mika Westerberg , "linux-pci@vger.kernel.org" References: <20190724133814.GA194025@google.com> From: Logan Gunthorpe Message-ID: <4f5afb8e-9013-980f-0553-c687d17ed8d5@deltatee.com> Date: Thu, 25 Jul 2019 09:50:48 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 68.147.80.180 X-SA-Exim-Rcpt-To: linux-pci@vger.kernel.org, mika.westerberg@linux.intel.com, benh@kernel.crashing.org, helgaas@kernel.org, nicholas.johnson-opensource@outlook.com.au X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: Possible PCI Regression Linux 5.3-rc1 X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 2019-07-25 7:18 a.m., Nicholas Johnson wrote: > On Wed, Jul 24, 2019 at 08:38:14AM -0500, Bjorn Helgaas wrote: >> On Wed, Jul 24, 2019 at 12:54:00PM +0000, Nicholas Johnson wrote: >>> Hi all, >>> >>> I was just rebasing my patches for linux 5.3-rc1 and noticed a possible >>> regression that shows on both of my machines. It is also reproducible >>> with the unmodified Ubuntu mainline kernel, downloadable at [1]. >>> >>> Running the lspci command takes 1-3 seconds with 5.3-rc1 (rather than an >>> imperceivable amount of time). Booting with pci.dyndbg does not reveal >>> why. >>> >>> $ uname -r >>> 5.3.0-050300rc1-generic >>> $ time lspci -vt 1>/dev/null >>> >>> real 0m2.321s >>> user 0m0.026s >>> sys 0m0.000s >>> >>> If none of you are aware of this or what is causing it, I will submit a >>> bug report to Bugzilla. >> >> I wasn't aware of this; thanks for reporting it! I wasn't able to >> reproduce this in qemu. Can you play with "strace -r lspci -vt" and >> the like? Maybe try "lspci -n" to see if it's related to looking up >> the names? > > For a second you had me doubting myself - it could have been a Ubuntu > thing. But no, I just reproduced it on Arch Linux, and double checked > that it was not doing it on 5.2. Also, the problem occurs even without > the PCI kernel parameters which I usually pass. Ok, can you bisect to find the commit that causes this issue? Thanks, Logan