Can't spawn jobs without /dev/null breaks mountall-dev which would create it; aka mountall: Event failed

Binary package hint: upstart

Hi

While trying to boot with a 2.6.30 kernel, I discovered that the system can't boot with /dev on tmpfs instead of devtmpfs.

The system starts with some useful devices in /dev, then upstart spawns mountall which mounts /dev as tmpfs (no devtmpfs available), then emits the mounted even with MOUNTPOINT=/dev TYPE=tmpfs. When upstart tries starting mounted-dev (which is "start on mounted /dev"), it fails to do so because there is no /dev/null.

Just creating /dev/null before emitting this event is enough to fix the problem (no other device is needed).

(This is despite mounted-dev.conf NOT using console output.)

I will probably move to 2.6.32 or backport devtmpfs support in my kernel, but another workaround to demonstrate the underlying problem is to change mountall.conf as follows:
#expect daemon
[...]

script
    . /etc/default/rcS
    [ -f /forcefsck ] && force_fsck="--force-fsck"
    [ "$FSCKFIX" = "yes" ] && fsck_fix="--fsck-fix"

    #exec mountall --daemon $force_fsck $fsck_fix
    mountall --verbose --no-events $force_fsck $fsck_fix
    mknod /dev/null char 1 3
    initctl emit --no-wait mounted MOUNTPOINT=/dev TYPE=tmpfs
    initctl emit --no-wait mounted MOUNTPOINT=/var/run TYPE=tmpfs
    initctl emit --no-wait mounted MOUNTPOINT=/tmp
    initctl emit --no-wait virtual-filesystems
    initctl emit --no-wait local-filesystems
    initctl emit --no-wait filesystem
    echo "sent all events"
end script

This boots fine.

Thanks,

ProblemType: Bug
Architecture: amd64
Date: Thu Jan 28 19:33:56 2010
DistroRelease: Ubuntu 10.04
Package: upstart 0.6.3-11build1
ProcEnviron:
 LANGUAGE=fr_FR.UTF-8
 PATH=(custom, user)
 LANG=fr_FR.UTF-8
 SHELL=/bin/zsh
ProcVersionSignature: Ubuntu 2.6.32-11.15-generic
SourcePackage: upstart
Uname: Linux 2.6.32-11-generic x86_64