From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758343Ab0FIVQk (ORCPT ); Wed, 9 Jun 2010 17:16:40 -0400 Received: from moutng.kundenserver.de ([212.227.126.171]:57457 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758302Ab0FIVQj (ORCPT ); Wed, 9 Jun 2010 17:16:39 -0400 From: arnd@arndb.de To: Ales Teska Subject: Re: PROBLEM: PPP and other serial port related application hangs in kernel space Date: Wed, 9 Jun 2010 23:16:32 +0200 User-Agent: KMail/1.13.2 (Linux/2.6.35-rc1-00090-g358f4b6; KDE/4.4.2; x86_64; ; ) Cc: linux-kernel@vger.kernel.org, Greg KH , Alan Cox References: <900E3B14-5B92-4A37-9581-049DB40F4D1C@gmail.com> In-Reply-To: <900E3B14-5B92-4A37-9581-049DB40F4D1C@gmail.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Message-Id: <201006092316.32497.arnd@arndb.de> X-Provags-ID: V01U2FsdGVkX19ebRUICGzwVh20z0ZAJ2gskxOxbeYKKrZLmBf 0S+ZeeFhDsnyjrzvo7rqdraenkP9L8gckF4yNeneLtHv+ZZWPN vClcsFiRy57YlD/197UvQ== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 09 June 2010 22:46:28 Ales Teska wrote: > after upgrade of Linux kernel to version 2.6.34 I started to observe following problem > - ppp and other serial port related application occasionally (in 1 hour or 1/10 ppp > connections) 'hangs' (see description bellow) rendering related serial device unusable. > I backtracked this issue to 2.6.32.15. > Application remains in the condition marked as 'D' in 'ps' output (waiting for result > from kernel space, if I understand that correctly); it stays in this condition forever. It would be good to find out where exactly the application hangs. Please try a sysrq-t (press Alt+SysRq+t simultaneously) or cat /proc//stack. It might also be helpful to try running the kernel with CONFIG_LOCKDEP and/or CONFIG_TTY_MUTEX enabled. For the latter one, you need to get the source from the tty branch of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl.git > I also found following information in dmesg: > [ 1673.660876] ------------[ cut here ]------------ > [ 1673.661471] WARNING: at drivers/char/tty_io.c:1278 tty_open+0x213/0x451() > [ 1673.662358] Modules linked in: ppp_deflate zlib_deflate bsd_comp ppp_async crc_ccitt ppp_generic slhc ipv6 nvram msr cpuid ledtrig_timer ledtrig_heartbeat ledtrig_default_on geodewdt lm90 hwmon scx200_acb option usbserial ehci_hcd ohci_hcd via_rhine usbcore leds_alix2 mii > [ 1673.689168] Pid: 1275, comm: ufoprobe_client Not tainted 2.6.34-486-exiprobes #1 > [ 1673.690452] Call Trace: > [ 1673.690947] [] ? tty_open+0x213/0x451 > [ 1673.691926] [] warn_slowpath_common+0x45/0x5c > [ 1673.693006] [] warn_slowpath_null+0xd/0x10 > [ 1673.694293] [] tty_open+0x213/0x451 > [ 1673.694755] [] chrdev_open+0xe3/0x126 Do you always see this message exactly once before it hangs? Arnd