From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754036Ab0BVAXq (ORCPT ); Sun, 21 Feb 2010 19:23:46 -0500 Received: from ozlabs.org ([203.10.76.45]:49886 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753801Ab0BVAXp (ORCPT ); Sun, 21 Feb 2010 19:23:45 -0500 From: Rusty Russell To: Alexey Dobriyan Subject: Re: hang in call_usermodehelper_exec() Date: Mon, 22 Feb 2010 10:53:32 +1030 User-Agent: KMail/1.12.2 (Linux/2.6.31-19-generic; KDE/4.3.2; i686; ; ) Cc: linux-kernel@vger.kernel.org References: <20100217202234.GD5256@x200> In-Reply-To: <20100217202234.GD5256@x200> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201002221053.32560.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 18 Feb 2010 06:52:34 am Alexey Dobriyan wrote: > I was stress-testing netns stuff in presence of removing modules. > > Kernel is 2.6.33-rc8-next-20100217+: > > At some point setkey(8) and modprobe hanged: > > 3541 pts/1 D 0:00 /usr/sbin/setkey -f /root/ipcomp-tunnel.setkey > 3737 pts/2 D 0:00 modprobe -r des_generic sha1_generic md5 hmac xfrm_user crypto_null af_packet xfrm4_mode_beet ipcomp xfrm_ipcomp xfrm4_tunnel deflate zlib_deflate zlib_inflate esp4 xfrm4_mode_tran Hmm, looks like sys_delete_module() is stuck trying to re-grab the module_mutex. But who's holding it? We'd need a full task dump to see. We do a stop_machine with the module mutex held, but not much else. This doesn't seem like that. Do you have tracepoints, or dynamic debug enabled? Puzzled, Rusty. -- Away travelling 25Feb-26Mar (6 .de + 1 .pl + 17 .lt + 2 .sg)