From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753219Ab2CaVfR (ORCPT ); Sat, 31 Mar 2012 17:35:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52464 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752927Ab2CaVfO (ORCPT ); Sat, 31 Mar 2012 17:35:14 -0400 Date: Sat, 31 Mar 2012 23:34:23 +0200 From: Oleg Nesterov To: Eric Dumazet Cc: Sasha Levin , davem@davemloft.net, kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, Patrick McHardy , netdev@vger.kernel.org, "linux-kernel@vger.kernel.org List" , Dave Jones , Tetsuo Handa Subject: Re: ipv6: tunnel: hang when destroying ipv6 tunnel Message-ID: <20120331213423.GA21219@redhat.com> References: <1333227549.2325.4051.camel@edumazet-glaptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1333227549.2325.4051.camel@edumazet-glaptop> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/31, Eric Dumazet wrote: > > On Sat, 2012-03-31 at 19:51 +0200, Sasha Levin wrote: > > Hi all, > > > > It appears that a hang may occur when destroying an ipv6 tunnel, which > > I've reproduced several times in a KVM vm. kernel version? > > [ 1561.564172] INFO: task kworker/u:2:3140 blocked for more than 120 seconds. And nobody else? It would be nice to know what sysrq-t says, in particular the trace of khelper thread is interesting. > Something is wrong here, call_usermodehelper_exec ( ... UMH_WAIT_EXEC) > should not block forever. Yes, unless it triggers another request_module()... Tetsuo, could you please take a look? Unlikely, but may be this is fixed by your kmod-avoid-deadlock-by-recursive-kmod-call.patch in -mm ? Oleg.