kernel BUG in drivers/tty/hvc/hvc_xen.c:69

During natty beta 2 testing, we had one occurrence of failed boot that had a kernel BUG in the console output. Reboot "fixed" the issue.

Below is the bug info:

[3828128.230767] ------------[ cut here ]------------
[3828128.230774] kernel BUG at /build/buildd/linux-2.6.38/drivers/tty/hvc/hvc_xen.c:69!
[3828128.230782] invalid opcode: 0000 [#1] SMP
[3828128.230789] last sysfs file: /sys/devices/virtual/vtconsole/vtcon0/uevent
[3828128.230795] CPU 3
[3828128.230798] Modules linked in:
[3828128.230804]
[3828128.230809] Pid: 1, comm: init Not tainted 2.6.38-8-virtual #42-Ubuntu
[3828128.230819] RIP: e030:[<ffffffff8139bff6>] [<ffffffff8139bff6>] domU_write_console+0x1a6/0x1b0
[3828128.230835] RSP: e02b:ffff8803a12cdca8 EFLAGS: 00010006
[3828128.230841] RAX: 0000000000003f77 RBX: 0000000000000025 RCX: 000000000000081b
[3828128.230848] RDX: 000000000000081b RSI: 0000000000000000 RDI: 0000000000000000
[3828128.230854] RBP: ffff8803a12cdd28 R08: ffff8800047fc000 R09: 0000000000000000
[3828128.230861] R10: 00007f9c90e57720 R11: 0000000000000000 R12: ffff880000000000
[3828128.230867] R13: ffff8803a12cdce8 R14: ffff8803a12cdccc R15: 0000000000000025
[3828128.230879] FS: 00007f9c90e57720(0000) GS:ffff8803bff90000(0000) knlGS:0000000000000000
[3828128.230887] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
[3828128.230892] CR2: 00007f9c90e56000 CR3: 000000039ed2f000 CR4: 0000000000002660
[3828128.230899] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[3828128.230906] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[3828128.230913] Process init (pid: 1, threadinfo ffff8803a12cc000, task ffff8803a12d0000)
[3828128.230919] Stack:
[3828128.230923] ffff8803a12cdcd8 ffffffff810447fc 0000000000000000 ffff88039f6dee80
[3828128.230934] ffff88039ed2d508 00007f9c90e56000 ffff8803a12cdd68 ffffffff8112c900
[3828128.230945] ffffffff810052dc ffff8803bfbf9f48 ffff88039ed2d508 ffff88039f6dee00
[3828128.230957] Call Trace:
[3828128.230966] [<ffffffff810447fc>] ? ptep_set_access_flags+0x6c/0x70
[3828128.230976] [<ffffffff8112c900>] ? do_wp_page+0xd0/0x770
[3828128.230985] [<ffffffff810052dc>] ? pte_mfn_to_pfn+0x8c/0xb0
[3828128.230992] [<ffffffff8139ae50>] hvc_push+0x20/0x70
[3828128.230998] [<ffffffff8139b109>] hvc_write+0xc9/0x100
[3828128.231008] [<ffffffff81383619>] process_output_block+0xb9/0x180
[3828128.231016] [<ffffffff81384410>] n_tty_write+0x150/0x280
[3828128.231023] [<ffffffff8105f180>] ? default_wake_function+0x0/0x20
[3828128.231031] [<ffffffff81380d21>] tty_write+0x1a1/0x270
[3828128.231037] [<ffffffff813842c0>] ? n_tty_write+0x0/0x280
[3828128.231044] [<ffffffff81380ea1>] redirected_tty_write+0xb1/0xc0
[3828128.231053] [<ffffffff81164176>] vfs_write+0xc6/0x180
[3828128.231059] [<ffffffff81164491>] sys_write+0x51/0x90
[3828128.231067] [<ffffffff8100bfc2>] system_call_fastpath+0x16/0x1b
[3828128.231072] Code: 75 88 48 39 c2 74 0d 48 89 d7 e8 a6 d0 c6 ff 48 89 c2 eb b5 48 89 f2 eb b0 4c 01 5d 98 31 ff 31 f6 e8 af 53 c6 ff e9 93 fe ff ff <0f> 0b 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 57 41 56 41 55 41
[3828128.231156] RIP [<ffffffff8139bff6>] domU_write_console+0x1a6/0x1b0
[3828128.231164] RSP <ffff8803a12cdca8>
[3828128.231171] ---[ end trace 996d2b80ff64bf0b ]---

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: linux-image-2.6.38-8-virtual 2.6.38-8.42
Regression: Yes
Reproducible: No
ProcVersionSignature: User Name 2.6.38-8.42-virtual 2.6.38.2
Uname: Linux 2.6.38-8-virtual x86_64
AlsaDevices:
 total 0
 crw------- 1 root root 116, 1 2011-04-14 13:50 seq
 crw------- 1 root root 116, 33 2011-04-14 13:50 timer
AplayDevices: Error: [Errno 2] No such file or directory
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory
CurrentDmesg: [3838852.532703] eth0: no IPv6 routers present
Date: Thu Apr 14 13:53:10 2011
Ec2AMI: ami-b6d07ab7
Ec2AMIManifest: ubuntu-images-testing-ap-northeast-1/ubuntu-natty-daily-amd64-server-20110413.1.manifest.xml
Ec2AvailabilityZone: ap-northeast-1b
Ec2InstanceType: m1.xlarge
Ec2Kernel: aki-d409a2d5
Ec2Ramdisk: unavailable
Frequency: This has only happened once.
Lspci:

Lsusb: Error: command ['lsusb'] failed with exit code 1:
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: root=LABEL=uec-rootfs ro console=hvc0
ProcModules: acpiphp 24097 0 - Live 0x0000000000000000
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)