Re: NET_NS: unregister_netdevice: waiting for lo to become free (after using openvpn)

On Thu, 05 Aug 2010 02:51:29 -0700
ebiederm@xmission.com (Eric W. Biederman) wrote:

Michael Leun [off-list ref] writes:

quoted

Hi,

On Wed, 04 Aug 2010 17:12:29 -0700
ebiederm@xmission.com (Eric W. Biederman) wrote:

First, thank you very much for picking that up (and, of course, for
your work at linux in general).

quoted

quoted

# > unshare -n /bin/bash
# > # how to setup veth device pair to get connectivity into
namespace not shown here # > openvpn --config some.config
[ running some traffic over vpn device not shown here ]
^c # stopping openvpn
# > lsof -i
# > netstat -an
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address
State Active UNIX domain sockets (servers and established)
Proto RefCnt Flags       Type       State         I-Node Path
# > ps ax|grep openvpn|grep -v grep
# > # cannot find anything that suggests there is anything left
from that openvpn session # > exit # logging out from shell in
network namespace

Now I get

Jul 10 20:02:36 doris kernel: unregister_netdevice: waiting for
lo to become free. Usage count = 3 [repeated]

How many times?

Unfortunately looks like indefinitely. Never watched longer so far
(rebooted soon), but I'm seeing this message now repeated every 10
secs for ~10 minutes on a idle system.

Ugh.  A real bug then.  These can be a pain to track down and fix. I
think the last one of these I tracked down took a couple of weeks.  I
will start digging in when I get back from vacation.

As I said, if I can do anything to support you, testing or so, please
let me know.

Until then: Have a great vacation!

quoted

Additionally when testing this I found another one (by accident
started my firewall script in that namespace...) - using netfilter
RECENT makes it barf. Stripped down to the essentials it looks like
this:

Micheal this is on 2.6.35?

Yup - almost vanilla 2.6.35, only patches for aufs (union filesystem)
got in.

Alexey can you look at this BUG_ON?  It looks like there has been a
regression or you missed something when you did the netns conversion
of xt_recent.

quoted

quoted

# unshare -n /bin/bash
# iptables -I INPUT -d 1.2.3.4 -m recent --name BLA --set
# exit

Aug  5 11:19:47 doris kernel: [  218.420238] ------------[ cut
here ]------------ Aug  5 11:19:47 doris kernel: [  218.420256]
kernel BUG at net/netfilter/xt_recent.c:609! Aug  5 11:19:47 doris

[...]

-- 
MfG,

Michael Leun