Re: NET_NS: unregister_netdevice: waiting for lo to become free (after using openvpn) (was Re: sysfs bug when using tun with network namespaces)

[Michael Leun <lkml20100708@newton.leun.net>]

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).


> > # > 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.

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:

> # 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 kernel: [  218.420268] invalid opcode: 0000 [#1] PREEMPT SMP 
Aug  5 11:19:47 doris kernel: [  218.420284] last sysfs file: /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0A:00/power_supply/BAT0/charge_full
Aug  5 11:19:47 doris kernel: [  218.420295] Modules linked in: snd_pcm_oss snd_mixer_oss snd_seq snd_seq_device edd cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf ipt_REJECT ipt_LOG xt_limit xt_recent iptable_mangle iptable_nat iptable_filter nf_conntrack_ipv6 xt_state xt_tcpudp ip6table_filter ip6_tables nf_nat_ftp nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack_ftp nf_conntrack ip_tables x_tables fuse nls_utf8 loop arc4 ecb iwlagn iwlcore mac80211 snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_pcm cfg80211 snd_timer snd usb_storage iTCO_wdt soundcore tg3 sg iTCO_vendor_support snd_page_alloc rfkill i2c_i801 pcspkr battery ac ext4 jbd2 crc16 sha256_generic aes_generic cbc dm_crypt linear i915 drm_kms_helper drm i2c_algo_bit sd_mod video 
 intel_agp button dm_snapshot dm_mod fan processor ata_piix ahci libahci libata scsi_mod thermal thermal_sys
Aug  5 11:19:47 doris kernel: [  218.420529] 
Aug  5 11:19:47 doris kernel: [  218.420542] Pid: 13, comm: netns Not tainted 2.6.35 #2 Kuril                           /40684JG         
Aug  5 11:19:47 doris kernel: [  218.420557] EIP: 0060:[<fc886a15>] EFLAGS: 00010206 CPU: 0
Aug  5 11:19:47 doris kernel: [  218.420578] EIP is at recent_net_exit+0x55/0x70 [xt_recent]
Aug  5 11:19:47 doris kernel: [  218.420589] EAX: f2218000 EBX: f5b79290 ECX: f2f27b40 EDX: f5cd4000
Aug  5 11:19:47 doris kernel: [  218.420601] ESI: f2218000 EDI: f5cd5f44 EBP: f5cd5f28 ESP: f5cd5f20
Aug  5 11:19:47 doris kernel: [  218.420612]  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
Aug  5 11:19:47 doris kernel: [  218.420626] Process netns (pid: 13, ti=f5cd4000 task=f5cc9920 task.ti=f5cd4000)
Aug  5 11:19:47 doris kernel: [  218.420635] Stack:
Aug  5 11:19:47 doris kernel: [  218.420641]  f5cd5f30 fc887618 f5cd5f3c c130867d fc887618 f5cd5f44 c1308850 f5cd5f60
Aug  5 11:19:47 doris kernel: [  218.420667] <0> c1308919 f2218014 f2218014 f221800c f221800c c15915a0 c3bb4f40 c1308850
Aug  5 11:19:47 doris kernel: [  218.420695] <0> f5cd5fbc c105a230 c13d1658 00000001 00000000 f7048000 c160f500 f5cc9c00
Aug  5 11:19:47 doris kernel: [  218.420724] Call Trace:
Aug  5 11:19:47 doris kernel: [  218.420749]  [<c130867d>] ? ops_exit_list+0x1d/0x50
Aug  5 11:19:47 doris kernel: [  218.420766]  [<c1308850>] ? cleanup_net+0x0/0x160
Aug  5 11:19:47 doris kernel: [  218.420782]  [<c1308919>] ? cleanup_net+0xc9/0x160
Aug  5 11:19:47 doris kernel: [  218.420797]  [<c1308850>] ? cleanup_net+0x0/0x160
Aug  5 11:19:47 doris kernel: [  218.420815]  [<c105a230>] ? worker_thread+0x110/0x250
Aug  5 11:19:47 doris kernel: [  218.420832]  [<c13d1658>] ? schedule+0x748/0x7a0
Aug  5 11:19:47 doris kernel: [  218.420849]  [<c105d5f0>] ? autoremove_wake_function+0x0/0x40
Aug  5 11:19:47 doris kernel: [  218.420864]  [<c105a120>] ? worker_thread+0x0/0x250
Aug  5 11:19:47 doris kernel: [  218.420879]  [<c105d1bc>] ? kthread+0x6c/0x80
Aug  5 11:19:47 doris kernel: [  218.420895]  [<c105d150>] ? kthread+0x0/0x80
Aug  5 11:19:47 doris kernel: [  218.420910]  [<c1003336>] ? kernel_thread_helper+0x6/0x10
Aug  5 11:19:47 doris kernel: [  218.420919] Code: 91 08 89 e2 81 e2 00 e0 ff ff 83 6a 14 01 f6 42 08 08 75 19 3b 1b 75 13 ba fa 72 88 fc e8 94 3e 8c c4 8d 64 24 04 5b 5d c3 0f 0b <0f> 0b 89 45 f8 e8 a1 ad b4 c4 8b 45 f8 eb da 8d b6 00 00 00 00 
Aug  5 11:19:47 doris kernel: [  218.421063] EIP: [<fc886a15>] recent_net_exit+0x55/0x70 [xt_recent] SS:ESP 0068:f5cd5f20
Aug  5 11:19:47 doris kernel: [  218.421136] ---[ end trace f57524f15f4df616 ]---


-- 
MfG,

Michael Leun