Comment 9 for bug 666211

Timo,
  If you're booting with the correct kernel (which it appears you are), then I can't imagine that bundle-vol and upload-bundle is what is causing this.
  I've seen similar issues to what is described here in bug 567334. There, I do not see the issue reproducibly, though.
  Do you see this in a easily reproducible manner ? I have some 368 logs of maverick ec2 boots in lp:~ubuntu-on-ec2/ubuntu-on-ec2/ec2-test-results/ (looking at files named console-term.txt). 8 of them have the 'jbd2/sda1...blocked' message but none of them show a hex dump like in the summary. Of those 8 all were x86_64 and instance-store, 2 of them m1.xlarge, 1 was c1.xlarge, 5 m1.large.

regarding rebundling, I would suggest using the images available at http://uec-images.ubuntu.com, mounting them loopback, making your changes via chroot, and then ec2-bundle-image and ec2-upload-bundle. This would especially be true if you're automating your changes. Its simply a cleaner starting point than a booted system, and will retain the filesystem label also.