linux-kernel - Linux Kernel Bug : rcu_preempt detected stalls on CPUs/tasks while connecting to openvpn on wireless connetion with IPv6

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Message-ID: <CAKAJyqs_Q7x1K_ohz3OAsWCnpgTDZYewNjHBYGh_WMXQVbnwYg@mail.gmail.com>
Date:	Thu, 29 Mar 2012 18:06:28 +0800
From:	"lynx.cpp@...il.com" <lynx.cpp@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: Linux Kernel Bug : rcu_preempt detected stalls on CPUs/tasks while
 connecting to openvpn on wireless connetion with IPv6

I am sorry for any grammar faults and confusing explanation , thus I
am not a native English speaker.

After booting and connecting to a WiFi access point with IPv6 , I
found my OpenVPN not starting normally.So I executed "sudo rc.d
restart openvpn".
It successfully stopped the daemon , and after that , it showing BUSY
for a long time. I executed "ifconfig" to see what was going on , but
I received no reply and the ifconfig didn't stop.
And I try to execute command "sudo" but it just ran and didn't give
any responses.
I used dmesg | less , and it said "
[  156.590039] INFO: rcu_preempt detected stalls on CPUs/tasks: {}
(detected by 0, t=18002 jiffies)
[  156.590047] INFO: Stall ended before state dump start
[  240.830609] INFO: task kworker/2:1:37 blocked for more than 120 seconds."

keywords : Networking , Kernel , IPv6 , WiFi , freezing

More information in dmesg is in the attachment "ipv6_error".
The output of "sudo lspci -vvv" is in "lspci".

The distribution I am using is Chakra(a project forked from Arch). I
am using KDE 4.8.1 as my desktop environment.
The version of kdeplasma-applets-networkmanagement(I use this to
connect to internet) is 0.8.95-2.
The version of NetworkManager is 0.9.2.0.

/proc/version  Linux version 3.2.13-1-pae (tomek@...robi) (gcc version
4.6.3 (GCC) ) #1 SMP PREEMPT Tue Mar 27 01:57:10 EDT 2012
uname -a          Linux lynx-chakra 3.2.13-1-pae #1 SMP PREEMPT Tue
Mar 27 01:57:10 EDT 2012 i686 Intel(R) Core(TM) i3-2310M CPU @ 2.10GHz
GenuineIntel GNU/Linux

The kernel I used is downloaded from "http://pae.archlinux.ca/".

This bug can be always reproduced whenever I use wireless IPv6. It can
be seldom reproduced when I use wired IPv6.

Download attachment "ipv6_error" of type "application/octet-stream" (14806 bytes)

Download attachment "lspci" of type "application/octet-stream" (24884 bytes)

Download attachment "modules" of type "application/octet-stream" (3421 bytes)