Boot broken with initramfs-tools 0.103ubuntu0.5b1 - wait-for-root doesn't wait

Status changed to 'Confirmed' because the bug affects multiple users.

The newest update to initramfs-tools, version 0.103ubuntu0.6 did not help.
Still dropping to busybox.
Commanding "exit" helps.

I run raring-proposed as well, and I cannot replicate this. But this does ring a bell. We got similar reports with earlier libudev0 versions as well, and eventually reverted an upstream commit:

http://bazaar.launchpad.net/~ubuntu-core-dev/ubuntu/quantal/udev/ubuntu/view/head:/debian/patches/libudev-revert-SOCK_NONBLOCK.patch

Unfortunately this never got debugged properly, as I never got access to a machine which exhibits this behaviour. Also, this works just fine on Debian, Fedora, Arch, and other distros, so I guess we have some bug in our initramfs-tools/upstart interaction which is exhibited by using a nonblocking socket. For now I'll apply that patch to libudev1.

As for the actual culprit, there are not that many things in the initramfs which use libudev1; most of them are from cryptsetup, but the most likely one is sbin/wait-for-root. This also has ubuntu specific modifications, so it's very likely that this doesn't get along with SOCK_NONBLOCK.

Ah, I got it. The documentation of udev_monitor_receive_device() says

  "The monitor socket is by default set to NONBLOCK. A variant of poll() on the file descriptor returned by udev_monitor_get_fd() should to be used to wake up when new devices arrive, or alternatively the file descriptor switched into blocking mode."

However, wait-for-root does

        while ((udev_device = udev_monitor_receive_device (udev_monitor)) != NULL) {

and then just exits. So switching the socket to blocking is indeed the right answer here.

I went through http://codesearch.debian.net/search?q=udev_monitor_receive_device and checked other users of this, and they are all ok (they all call this from a callback). So let's fix this in wait-for-root, and get rid of this Ubuntu specific ABI change.

Martin Pitt wrote:
"... but the most likely one is sbin/wait-for-root."

Exactly this is the issue.
The error message I get before dropping to busybox shell is
Gave up waiting for root.
And then I get the Alert that the root UUID does not exist.

I uploaded a fix to raring-proposed:

initramfs-tools (0.103ubuntu0.7) raring; urgency=low

  * src/wait-for-root.c: Set udev monitor socket to blocking, as we want to
    wait for events. (LP: #1154813)

 -- Martin Pitt <email address hidden> Thu, 14 Mar 2013 07:08:06 +0100

I close the bug as this only affects raring-proposed, not raring. Jean-Louis, I'd be grateful if you could confirm that this works properly for you now?

Thanks, and sorry for the hassle!

Just tested this, and it seems to work fine.

Thanks for the fix!

I can also confirm that the latest initramfs-tools fixes the problem for me.