Setting up memtest86+ hangs because of "grub-probe: error: unknown filesystem"

[Laurent Riffard]

Installation of package memtest86+ fails, it does hang and never ends if lvm snapshot is present.

Prepare:
* create active lvm snapshot

Test case:
$ sudo apt-get install --reinstall memtest86+

<hang>

Recover from the hang with:
$ sudo pkill -f 'frontend /var/lib/dpkg/info/memtest86\+.postinst'
$ sudo killall grub-mount
$ sudo umount /var/lib/os-prober/mount

(don't kill grub-mount nor umount if you want the next run to "succeed", well not run)

Actual problem:
update-grub / os-prober leave stray grub-mount behing.
workarounds applied in os-prober 1.57 doesn't actually help here.
upgrading to quantal's grub2 package resolves the hangs.
A minimal backport from grub has not been identified yet.

[Laurent Riffard (laurent-riffard)]

This evening, I noticed that "dpkg --configure memtest86 +" produced a "grub-mount" process :

# ps axf
[...]
21980 pts/2 S+ 0:00 \_ sudo apt-get -f install
21981 pts/2 S+ 0:01 \_ apt-get -f install
21989 pts/4 Ss+ 0:00 \_ /usr/bin/dpkg --status-fd 67 --configure memtest86+:amd64 ubuntu-standard:amd64
21990 pts/4 S+ 0:00 \_ /usr/bin/perl -w /usr/share/debconf/frontend /var/lib/dpkg/info/memtest86+.postinst configure 4.20-1ubuntu1
21997 pts/4 Z+ 0:00 \_ [memtest86+.post] <defunct>
[...]
23816 ? Ss 0:00 grub-mount /dev/mapper/vglinux1-lv_ubunutu_oneiric /var/lib/os-prober/mount
[...]

Killing this "grub-mount" process allows dpkg to complete successfully.

So the problem was not the Reiser4 filesystems, it was the LVM snapshot.

# lvdisplay /dev/mapper/vglinux1-lv_ubunutu_oneiric
  --- Logical volume ---
  LV Name /dev/vglinux1/lv_ubunutu_oneiric
  VG Name vglinux1
  LV UUID e8GxvT-YwJx-HQXW-ryD9-5zya-tI0g-J7Qosz
  LV Write Access read/write
  LV snapshot status active destination for /dev/vglinux1/lv_ubuntu
  LV Status available
  # open 0
  LV Size 10,00 GiB
  Current LE 2560
  COW-table size 10,00 GiB
  COW-table LE 2560
  Allocated to snapshot 50,56%
  Snapshot chunk size 512,00 KiB
  Segments 2
  Allocation inherit
  Read ahead sectors auto
  - currently set to 256
  Block device 252:13

[Launchpad Janitor (janitor)]

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

[Sylwester (ubuntulinux-org)]

My upgrade from oneiric to precise has been hanging for 8 hours because of this bug. I also have made a snapshot of my EXT4 root. I'm unsure but /etc/fstab in this snapshot will point to the same drives so grub-mount might try to mount something already mounted elsewhere maybe??

[Rob Hasselbaum (rhasselbaum)]

Same issue. I also took an LVM snapshot of root before upgrading, so it does seem that's the trigger. Ironic.

[pipe (pipatron)]

I just upgraded to precise, and found my computer with this memtest-issue after several hours. I did *not* take a snapshot of my root, but my root is on a logical volume on an encrypted physical volume. I had to perform the same kill as the original reporter did.

I am continuing the upgrade now, seemingly without any issues.

[pipe (pipatron)]

Now it happened again, at the "Cleaning up" part of the upgrade.

I suspect it has nothing to do with memtest. It might be that memtest is the last thing it sees, and perhaps os-prober is the culprit.

[Karl Maier (w-wall2001)]

Thanks, killing grub-mount did the trick for me. Bug #986833 might be related. My error message when the computer hang was

...
Found memtest86+ image: /memtest86+.bin
File descriptor 3 (pipe:[15340]) leaked on lvs invocation. Parent PID 4755: /bin/sh
rmdir: konnte »/var/lib/os-prober/mount“ nicht entfernen: Das Gerät oder die Ressource ist belegt
rmdir: konnte »/var/lib/os-prober/mount“ nicht entfernen: Das Gerät oder die Ressource ist belegt
grub-probe: Fehler: no such disk.

[Manuel (manuel-vacelet)]

I got the same issue when upgrading from 11.10 to 12.04, always on memtest. Killing grub-mount work around the issue.

I just got an upgrade of the kernel and I got the same issue.

I'm not using LVM. Just plain ext4 partition on a goo'old macbook 5.1

[Daniel Smedegaard Buus (danielbuus)]

In my case, grub was trying to mount an eSATA connected NTFS drive and hanging there.

[Launchpad Janitor (janitor)]

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

[Arthur Widetschek (arthur-widetschek)]

Ubuntu 13.04 Raring 64 Bit, btrfs
update-grub hangs at memtest86+
Ubuntu does not start.
My workaround: copied the old grub.cfg into /boot/grub/

[taka k. (scar)]

how do we permanently fix this? the pkill -f 'frontend /var/lib/dpkg/info/memtest86\+.postinst' command recovers from the hang, but memtest86+ is still not properly installed, and hangs everytime 'dpkg --configure' is called, or when kernel is updated, etc.

[taka k. (scar)]

why did you release a fix for the non-LTS releases but Precise is still waiting? very frustrated....

[taka k. (scar)]

hello how do we fix this on 12.04?

[Eric (eric-woodruff)]

Killing grub-mount (there were like 5 running on an upgrade to 15.04) allowed the upgrade to continue.

[Steve Langasek (vorlon)]

The Precise Pangolin has reached end of life, so this bug will not be fixed for that release

[Vadim Peretokin (vperetokin)]

It's still a problem when upgrading from 21.04 to 21.10, grub-mount hung trying to query an unresponsive drive.