System crashes if disconnected from network

[Cody A.W. Somerville]

After upgrading to Feisty, I have an interesting new feature where if the box is disconnected from the Network then the computer freezes completely (music stops playing, won't respond to mouse input, won't respond to keyboard input, gui freezes, etc.) and the caps lock and scroll lock leds flash. This has occurred several times but is not reproducible everytime. It has only started to occur after I upgraded to Feisty.

Whats even more scary is that there have also beens time when this has occurred but the above mentioned trigger did _not_ occur! ie. Something else caused it to freeze up like this.

I'd be happy to help test and debug this anyway I can. I tried looking in the log files for some indication of an error but none were found.

[Cody A.W. Somerville (cody-somerville)]

This evening I was fooling around with this to see if I could uncover any more clues (ie. I had noticed that music was usually playing when the crash occurred so I tried unplugging it with different players running in attempt to get it to crash again - but this was unsuccessful) . I found out that it does not occur every time the network is disconnected (description updated).

At the end of the night, I tried unplugging it and plugging it back one more time (nothing happened) before I clicked Applications > Quit in Xubuntu and clicked shutdown. After X closed, I was presented with scrolling text that repeated the following:

"atkdbd.c: Spurious ACK on isa0060/serio0. Some program might be trying to access hardware directly."

At the same time, the caps and scroll lock leds were flashing (like in the other freezes). A fellow on IRC had suggested that I try a few different key combinations with alt+ctrl+shift+sysrq+<blah> or something to that effect and I tried it with b (which he told me, and which I lated tried for myself to success, rebooted the system). At this time, I was presented with something that looked like a traceback at the top of the screen and two forward slashes at the bottom of he screen. The leds had stopped blinking and no input was the keyboard seemed to register.

The traceback was as following (though I copied it by hand so there might be some user errors):

[<d0c4c060>] device_cmp+0x0/0x50 [ipt_MASQUERADE]
[<d0c5c04d>] musq_inet_event+0x1d/0x20 [ipt_MASQUERADE]
[<c02e8655>] notifier_call_chain+0x25/0x30
[<c0131ab5>] blocking_notifier_call_chain+0x25/40
[<c02bfa4f>] __inet_del_ifa+0x11f/0x220
[<c02c0c6e>] devinet_ioctl+0x28c/0x6c0
[<x026e25f >] sock_ioctl+0xbf/0x210
[<c026ela0 >] sock_ioctl+0x0/0x210
[<c017eb0b>] do_ioctl+0x2b/0x90
[<c017ebcc>] vfs_ioctl+0x5c/0x2a0
[<c017ee8c>] sys_ioctl+0x5c/0x2a0
[<c0103116>] sysenter_past_esp+0x5f/0x89
[<c02e0033>] vcc_connect+0x1b3/0x580
                         ===========================

I hope this helps and sorry if I cause you any due confusion and stress is I made a typo in there! If the above incident is a separate bug, please let me know and I'll create a new bug report.

[Freddy Martinez (freddymartinez9)]

I've had this happen on my system. I was using Feisty Herd 1 and my network went down (not unplugged cables, the actual network) and then my system hardlocked. I couldn't do anything and had to restart my computer to get it to work.

[Cody A.W. Somerville (cody-somerville)]

I think the issue may be related to IPT.

[Michael Mc Donnell (michael-mcdonnell)]

I got the same error. Hard freeze(eg. no SysRq) with caps lock and scroll lock blinking. The last messages in my kernel log had something to do with networking:

Jun 3 22:14:55 localhost kernel: [46944.784919] Inbound IN=eth0 OUT= MAC=00:c0:26:27:15:03:00:02:3f:75:2c:3b:08:00 SRC=172.16.0.21 DST=172.16.3.10 LEN=48 TO
S=0x00 PREC=0x00 TTL=128 ID=19287 DF PROTO=TCP SPT=1331 DPT=139 WINDOW=65535 RES=0x00 SYN URGP=0
Jun 3 22:14:58 localhost kernel: [46947.696460] Inbound IN=eth0 OUT= MAC=00:c0:26:27:15:03:00:02:3f:75:2c:3b:08:00 SRC=172.16.0.21 DST=172.16.3.10 LEN=48 TO
S=0x00 PREC=0x00 TTL=128 ID=19441 DF PROTO=TCP SPT=1331 DPT=139 WINDOW=65535 RES=0x00 SYN URGP=0
Jun 3 22:15:04 localhost kernel: [46953.706803] Inbound IN=eth0 OUT= MAC=00:c0:26:27:15:03:00:02:3f:75:2c:3b:08:00 SRC=172.16.0.21 DST=172.16.3.10 LEN=48 TO
S=0x00 PREC=0x00 TTL=128 ID=19753 DF PROTO=TCP SPT=1331 DPT=139 WINDOW=65535 RES=0x00 SYN URGP=0

I run Feisty with a 2.6.20-16-386 kernel. I have the following hardware:

00:00.0 Host bridge: VIA Technologies, Inc. VT8377 [KT400/KT600 AGP] Host Bridge
00:01.0 PCI bridge: VIA Technologies, Inc. VT8235 PCI Bridge
00:09.0 Ethernet controller: Broadcom Corporation BCM4401 100Base-T (rev 01)
00:0a.0 Multimedia video controller: Brooktree Corporation Bt878 Video Capture (rev 11)
00:0a.1 Multimedia controller: Brooktree Corporation Bt878 Audio Capture (rev 11)
00:0b.0 Multimedia audio controller: Creative Labs SB Live! EMU10k1 (rev 07)
00:0b.1 Input device controller: Creative Labs SB Live! Game Port (rev 07)
00:0e.0 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 50)
00:0e.1 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 50)
00:0e.2 USB Controller: VIA Technologies, Inc. USB 2.0 (rev 51)
00:0f.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)
00:10.0 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 80)
00:10.1 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 80)
00:10.2 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 80)
00:10.3 USB Controller: VIA Technologies, Inc. USB 2.0 (rev 82)
00:11.0 ISA bridge: VIA Technologies, Inc. VT8235 ISA Bridge
00:11.1 IDE interface: VIA Technologies, Inc. VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 06)
01:00.0 VGA compatible controller: nVidia Corporation NV44A [GeForce 6200] (rev a1)

I'm using the Realtek nic and the Broadcom isn't connected.

[Brian Murray (brian-murray)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. The issue that you reported is one that should be reproducable with the live environment of the Desktop CD of the development release - Gutsy Gibbon. It would help us greatly if you could test with it so we can work on getting it fixed in the actively developed kernel. You can find out more about the development release at http://www.ubuntu.com/testing/ . Thanks again and we appreciate your help.