aufs au_new_inode:412:cc1[11919]: Warning: Un-notified UDBA or repeatedly renamed dir

I've started seeing AUFS errors on my system during sbuilds. Sometimes it will trigger a build failure. I do not seem to be able to reproduce the issue at will, unfortunately.

This was seen while trying to build qemu-kvm:

[69828.939172] aufs au_new_inode:412:cc1[11919]: Warning: Un-notified UDBA or repeatedly renamed dir, b0, ext4, qemu-kvm-0.12.5+noroms, hi3801956, i9640.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: linux-image-2.6.38-3-generic 2.6.38-3.30
Regression: Yes
Reproducible: No
ProcVersionSignature: Ubuntu 2.6.38-3.30-generic 2.6.38-rc4
Uname: Linux 2.6.38-3-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
AplayDevices:
 **** List of PLAYBACK Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: ALC268 Analog [ALC268 Analog]
   Subdevices: 0/1
   Subdevice #0: subdevice #0
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: kees 2551 F.... pulseaudio
 /dev/snd/pcmC0D0p: kees 2551 F...m pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xe0420000 irq 48'
   Mixer name : 'Realtek ALC268'
   Components : 'HDA:10ec0268,80860000,00100003'
   Controls : 17
   Simple ctrls : 11
Date: Fri Feb 11 15:50:32 2011
Frequency: Once a day.
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.UTF-8
 LC_MESSAGES=en_US.utf8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-2.6.38-3-generic root=/dev/mapper/systemvg-root2lv ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-2.6.38-3-generic N/A
 linux-backports-modules-2.6.38-3-generic N/A
 linux-firmware 1.46
RfKill:

SourcePackage: linux
WpaSupplicantLog:

dmi.bios.date: 09/22/2008
dmi.bios.vendor: Intel Corp.
dmi.bios.version: JOQ3510J.86A.0954.2008.0922.2331
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: DQ35JO
dmi.board.vendor: Intel Corporation
dmi.board.version: AAD82085-800
dmi.chassis.type: 3
dmi.modalias: dmi:bvnIntelCorp.:bvrJOQ3510J.86A.0954.2008.0922.2331:bd09/22/2008:svn:pn:pvr:rvnIntelCorporation:rnDQ35JO:rvrAAD82085-800:cvn:ct3:cvr: