From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754205AbaCJTXU (ORCPT ); Mon, 10 Mar 2014 15:23:20 -0400 Received: from mailout32.mail01.mtsvc.net ([216.70.64.70]:51186 "EHLO n23.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753998AbaCJTXS (ORCPT ); Mon, 10 Mar 2014 15:23:18 -0400 Message-ID: <531E111A.8040207@hurleysoftware.com> Date: Mon, 10 Mar 2014 15:23:06 -0400 From: Peter Hurley User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Sree Harsha Totakura CC: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Oleg Nesterov Subject: Re: pppd service crash in linux-3.13.6 References: <531A37FF.4000509@totakura.in> <531DEEA6.4090808@totakura.in> In-Reply-To: <531DEEA6.4090808@totakura.in> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated-User: 990527 peter@hurleysoftware.com X-MT-ID: 8FA290C2A27252AACF65DBC4A42F3CE3735FB2A4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ +cc Oleg Nesterov ] On 03/10/2014 12:56 PM, Sree Harsha Totakura wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hi, > > Using linux-3.13.6, I am observing the following output from the pppd > kernel thread. This happens when I try to suspend my computer and it > *stops* the computer from suspending. > > I am using ppp via a bluetooth modem. > > Trace: > [22735.115313] PM: Syncing filesystems ... done. > [22735.665613] PM: Preparing system for mem sleep > [22735.665829] Freezing user space processes ... > [22755.659538] Freezing of tasks failed after 20.004 seconds (1 tasks > refusing to freeze, wq_ > busy=0): > [22755.659555] pppd D ffff8800376c9a58 0 16801 1 > 0x00000006 > [22755.659557] ffff8800376c9750 0000000000000046 0000000000012e80 > 0000000000012e80 > [22755.659560] ffff8802a1c1dfd8 ffff8800376c9750 0000000000000009 > ffff8802a1c1dd78 > [22755.659562] 0000000000000046 ffff8800376c9750 0000000000000028 > ffff8800376c9750 > [22755.659564] Call Trace: > [22755.659569] [] ? do_exit+0x937/0xa50 > [22755.659573] [] ? oops_end+0x91/0xd0 > [22755.659575] [] ? no_context+0x1f3/0x1ff > [22755.659577] [] ? __do_page_fault+0x89/0x500 > [22755.659581] [] ? free_pcppages_bulk+0x17c/0x3b0 > [22755.659584] [] ? free_hot_cold_page_list+0x3e/0x90 > [22755.659586] [] ? page_fault+0x28/0x30 > [22755.659591] [] ? ppp_register_channel+0x13/0x20 > [ppp_generic] > [22755.659594] [] ? ppp_asynctty_open+0x12b/0x170 > [ppp_async] > [22755.659596] [] ? tty_ldisc_open.isra.2+0x27/0x60 > [22755.659598] [] ? tty_ldisc_hangup+0x1e3/0x220 > [22755.659601] [] ? __tty_hangup+0x2c4/0x440 > [22755.659603] [] ? disassociate_ctty+0x61/0x270 > [22755.659605] [] ? do_exit+0x7f2/0xa50 > [22755.659607] [] ? recalc_sigpending+0x12/0x50 > [22755.659609] [] ? __set_task_blocked+0x28/0x70 > [22755.659611] [] ? do_group_exit+0x34/0xa0 > [22755.659613] [] ? SyS_exit_group+0xb/0x10 > [22755.659615] [] ? system_call_fastpath+0x16/0x1b > [22755.659618] > [22755.659619] Restarting tasks ... done. > > If you need any more info, I am happy to provide. The NULL ptr dereference is from following the current->nsproxy ptr in ppp_register_channel(). This was broken by commit 8aac62706adaaf0fab02c4327761561c8bda9448 Author: Oleg Nesterov Date: Fri Jun 14 21:09:49 2013 +0200 move exit_task_namespaces() outside of exit_notify() which moved the exit_task_namespaces(tsk) before disassociate_ctty(). Regards, Peter Hurley