From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756105AbZE0BA2 (ORCPT ); Tue, 26 May 2009 21:00:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752168AbZE0BAU (ORCPT ); Tue, 26 May 2009 21:00:20 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:36215 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751229AbZE0BAT (ORCPT ); Tue, 26 May 2009 21:00:19 -0400 To: Andrew Morton Cc: Matheus Izvekov , linux-kernel@vger.kernel.org References: <20090521202655.GA13944@izvekov> <20090526165416.9078d218.akpm@linux-foundation.org> From: ebiederm@xmission.com (Eric W. Biederman) Date: Tue, 26 May 2009 18:00:12 -0700 In-Reply-To: <20090526165416.9078d218.akpm@linux-foundation.org> (Andrew Morton's message of "Tue\, 26 May 2009 16\:54\:16 -0700") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=76.21.114.89;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 76.21.114.89 X-SA-Exim-Rcpt-To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, mizvekov@gmail.com X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-DCC: XMission; sa02 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Andrew Morton X-Spam-Relay-Country: X-Spam-Report: * -1.8 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -0.2 BAYES_40 BODY: Bayesian spam probability is 20 to 40% * [score: 0.3315] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa02 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 XM_SPF_Neutral SPF-Neutral * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay Subject: Re: [BUG] parport issue on 2.6.29 X-SA-Exim-Version: 4.2.1 (built Thu, 25 Oct 2007 00:26:12 +0000) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton writes: > On Thu, 21 May 2009 17:26:55 -0300 > Matheus Izvekov wrote: > >> This warning happens whenever a specific parallel port control app is run >> without a device attached to it. After the first timeout, the app hangs, >> and needs SIGKILL to exit. >> >> WARNING: at kernel/sysctl.c:2021 unregister_sysctl_table+0xa3/0x110() > > I guess this is > > void unregister_sysctl_table(struct ctl_table_header * header) > { > might_sleep(); > > if (header == NULL) > return; > > spin_lock(&sysctl_lock); > start_unregistering(header); > if (!--header->parent->count) { > WARN_ON(1); > >> Hardware name: >> Modules linked in: >> Pid: 12161, comm: x-killer.exe Not tainted 2.6.29.4 #14 >> Call Trace: >> [] warn_slowpath+0xd0/0x130 >> [] ? sched_clock_cpu+0xb9/0x190 >> [] ? try_to_wake_up+0x174/0x330 >> [] ? up+0x34/0x50 >> [] ? release_console_sem+0x1bd/0x210 >> [] ? printk+0x67/0x69 >> [] unregister_sysctl_table+0xa3/0x110 >> [] parport_device_proc_unregister+0x28/0x40 >> [] parport_unregister_device+0x15/0x180 >> [] pp_release+0xbc/0x1f0 >> [] __fput+0xc3/0x1e0 >> [] fput+0x1d/0x30 >> [] filp_close+0x50/0x80 >> [] put_files_struct+0x84/0xe0 >> [] exit_files+0x4e/0x60 >> [] do_exit+0x196/0x930 >> [] do_group_exit+0x3e/0xb0 >> [] get_signal_to_deliver+0x2a4/0x420 >> [] do_notify_resume+0xba/0x900 >> [] ? __wake_up+0x4e/0x70 >> [] ? getnstimeofday+0x59/0xe0 >> [] ? ktime_get_ts+0x59/0x60 >> [] ? compat_sys_futex+0xb4/0x140 >> [] int_signal+0x12/0x17 >> --[ end trace ff1bd583c825c0c5 ]--- >> pdev0: unregistered pardevice > > > > Eric, can you please help decode the reason for this kernel warning? Looks like fallout from when Al changed the semantics of sysctl. Requiring sysctl tables to hang off of empty parent directories. It looks the parent directory was already been unregistered by the time we are unregistered. I'm not current enough on the parport code to have a better clue. As far as sysctl goes that condition should be essentially harmless, wrong but harmless. Eric