Bug#735935: grub2: LVM trouble at boot after upgrade to 2.02 beta

[Colin Watson]

On Sat, Jan 18, 2014 at 03:20:11PM -0500, Geoffrey Thomas wrote:
> I have the strangest issue which I am not even entirely confident is
> a GRUB issue, but it started right after upgrading my system to GRUB
> 2.02 from experimental, and without other changes, and it's even
> reproducible when running my system inside kvm off a thumbdrive, so
> I'm going to provisionally blame it on the GRUB 2.02 beta build.
> 
> I'm running a pretty standard LVM setup -- there's other stuff on
> this hard disk (like the preinstalled Windows), but one of the
> MS-DOS partitions is an LVM PV, containing a VG named "leveret",
> containing two LVs named "root" and "swap". /boot itself is located
> on the "root" LV. Every time I start up, since the upgrade, the
> initramfs fails to find my root hard disk via its /dev/disk/by-uuid
> path, and dumps me to a shell. If I look inside /dev/mapper, I see a
> node for "leveret-swap" but not "leveret-root". `lvm lvs` happily
> lists both nodes, though, and I can get my system to boot if I do
> `lvm vgchange -an`, `lvm vgchange -ay` (at which point both nodes
> appear, as well as the by-uuid symlink), and `exit`.
> (Resume-from-hibernate even worked after doing this, right after the
> upgrade.) There's nothing particularly suspicious-sounding in dmesg
> at any point.
> 
> The machine is a Toshiba L635 laptop, a few years old, BIOS boot
> only, running a somewhat out-of-date Debian testing, amd64. I'm
> running linux-image-3.9-1-amd64 3.9.8-1 (from testing this past
> summer or so) and lvm2 2.02.95-7. I'm happy to try to upgrade these,
> but since I haven't upgraded anything else on the system for a few
> weeks, I figured I'd report this and leave the system alone in case
> you had more questions about the current setup.

Thanks for preserving the evidence!

There are really not very many ways in which GRUB gets to affect the
behaviour of the running kernel.  The most obvious one is the kernel
command line.  Have you compared these before and after?  IIRC we use
LVM UUIDs more aggressively in 2.02 than in 2.00; see e.g. commit
63653cfdae32648c93870fd36b2925346aa8ff36.  I'm not exactly sure what
parts of userspace this relies on.

-- 
Colin Watson                                       [cjwatson at debian.org]