I confirm this issue on Ubuntu Server 12.04.2 LTS with udev version 175-0ubuntu9.3
Here, apt-get dist-upgrade hangs in udev start of update post-install phase with the same strace as in the description.
Reading through the Turnkey Linux forum thread referenced in comment #1, I was able to resolve the deadlock by "service udev stop" in another terminal, while the update still hangs in udev start. This hangs too, but now the update continues and succeeds. Last, I had to terminate the stop command by hitting Ctrl-C
I confirm this issue on Ubuntu Server 12.04.2 LTS with udev version 175-0ubuntu9.3
Here, apt-get dist-upgrade hangs in udev start of update post-install phase with the same strace as in the description.
Reading through the Turnkey Linux forum thread referenced in comment #1, I was able to resolve the deadlock by "service udev stop" in another terminal, while the update still hangs in udev start. This hangs too, but now the update continues and succeeds. Last, I had to terminate the stop command by hitting Ctrl-C