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=-5.2 required=3.0 tests=BAYES_00, 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 F2313C63697 for ; Mon, 16 Nov 2020 17:06:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C568420789 for ; Mon, 16 Nov 2020 17:06:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732487AbgKPRG1 (ORCPT ); Mon, 16 Nov 2020 12:06:27 -0500 Received: from netrider.rowland.org ([192.131.102.5]:44461 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1732195AbgKPRG0 (ORCPT ); Mon, 16 Nov 2020 12:06:26 -0500 Received: (qmail 442206 invoked by uid 1000); 16 Nov 2020 12:06:25 -0500 Date: Mon, 16 Nov 2020 12:06:25 -0500 From: Alan Stern To: Alberto Sentieri <22t@tripolho.com> Cc: Greg Kroah-Hartman , linux-usb@vger.kernel.org Subject: Re: kernel locks due to USB I/O Message-ID: <20201116170625.GC436089@rowland.harvard.edu> References: <9428ae70-887e-b48b-f31c-f95d58f67c61@tripolho.com> <20201110205114.GB204624@rowland.harvard.edu> <8152190e-c962-e376-64fd-cc2ebf3e6104@tripolho.com> <20201111155130.GB237113@rowland.harvard.edu> <9687fac9-94de-50a3-f88e-b7e05d660aba@tripolho.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9687fac9-94de-50a3-f88e-b7e05d660aba@tripolho.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Mon, Nov 16, 2020 at 11:53:38AM -0500, Alberto Sentieri wrote: > The objective of this email is to report the current status of my findings. > > I loaded netconsole on both machines I was having problems with. I tried 3 > times on the machine with kernel 5.0.0-37 and twice with on the machine with > kernel 5.3.0-62. Each attempt consisted of running the program which lock > the kernel until it locked (about 3 minutes after stating the program). The > referred program had the "semphore code" commented out. Nothing was sent to > netconsole on all the 5 attempts I made when the kernel locked. > > Just to be clear about my use of netconsole, before loading the netconsole > kernel module, I ran "dmesg -n 8". When netconsole module was loaded I could > clearly see about 9 message lines on the computer receiving the netconsole > messages telling me that netconsole was loaded (and how it was configured), > so no doubts about the correct netconsole setup. The "netconsole server" was > a machine on the same local network. > > My next attempt will be to compile kernel 5.9, as you suggest, and try it. While this may not generate any useful information, one way to create a bunch of log output while running your test is to set the usbfs_snoop module parameter for usbcore to true. You can also enable dynamic debugging for usbcore, although in a stable environment like yours it probably won't produce much output. Alan Stern