On Tue, 04 Dec 2007 21:17:01 PST, Andrew Morton said:
>   ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.24-rc4/2.6.24-rc4-mm1/

Something in here broke LVM support - an initrd that has worked fine for
quite some time suddenly couldn't mount /dev/VolGroup00/root so we get the
infamous "Kernel panic - not syncing: Attempted to kill init!" when we
fall off the end of the initrd and haven't pivoted to the real disk.

It finds the disk OK:

[   81.202310] sd 0:0:0:0: [sda] 156301488 512-byte hardware sectors (80026 MB)
[   81.214466] sd 0:0:0:0: [sda] Write Protect is off
[   81.226467] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[   81.238436] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[   81.250780]  sda: sda1 sda2
[   75.396119] sd 0:0:0:0: [sda] Attached SCSI disk

but then the lvm command says it can't find the volume group VolGroup00 (which
is actually sda2 - sda1 is a small /boot partition, rest of disk is LVM).

A quick look at the rc4-mm1 announcement doesn't have any obviously tempting
patch names to start at, so it looks like it's time to play mm-bisect.  It may
take me a day or two, as I have some time management issues this week...