/oldroot fails to unmount, shutdown unaffected

twoexem · 2022-03-21 09:29:52

Hello!

I'm having a small issue with both of my PCs running Arch. It doesn't halt shutdown completely but just looks a bit annoying.
One PC is a Medion E2291 notebook, one is a custom rig with an AMD GPU & CPU.
I'm running the stock kernel.

Everytime Plymouth finishes displaying its splashscreen, this gets displayed:

 [   250.982832 ]  sd-umount[1177]: Failed to unmount /oldroot: Device or resource busy
 [   250.983401 ]  sd-umount[1178]: Failed to unmount /oldroot/dev: Device or resource busy
 [   250.984415 ]  shutdown[1]: Failed to finalize file systems, ignoring.

It doesn't halt the shutdown and only gets displayed for a brief moment, but I'm still wondering what exactly causes this. Other forum threads mentioned it has something to do with NVidia drivers, but I don't have a NVidia GPU in either of the two PCs. If anybody needs additional system information, I'll happily provide it.

ratcheer · 2022-03-21 13:04:33

I always get these messages at shutdown, too.

/oldroot is not mounted when my system is running, and there is nothing about /oldroot in my fstab

Scimmia · 2022-03-21 13:33:55

During shutdown, the system pivots to a ramfs image, and your actual root partition is on /oldroot. It generally can't unmount it because it's still busy, something is open.

twoexem · 2022-03-21 13:35:38

Ah, I see. Doesn't systemd kill all processes at shutdown, though? And how can I check if / which program is still running at that moment?

Maniaxx · 2022-03-21 13:37:44

'oldroot' is the 'root' created initially by initramfs and later overmounted by real root. The errors (at least for nvidia) should be harmless as the initramfs is read-only and unchangeable anyway. The messages might be caused by custom modules added to the initramfs that can't be unloaded properly anymore.

To debug this one could maybe replace the shutdown service/command with some debug output.

Last edited by Maniaxx (2022-03-21 13:46:34)

WorMzy · 2022-03-21 14:12:59

Check the last few messages from the previous boot session's journal:

# journalctl -b-1

Perhaps something is recorded there that could explain why your root partition is still busy.

slick3371 · 2022-03-22 23:05:36

I have been having the same issue. From what I've experienced, the issue seems to happen only when either Plymouth is installed, or when /etc/mkinitcpio.conf contains the plymouth hook. I also cannot find this error in journalctl.

twoexem · 2022-05-04 06:30:03

WorMzy wrote:

Check the last few messages from the previous boot session's journal:
# journalctl -b-1
Perhaps something is recorded there that could explain why your root partition is still busy.

Trying that doesn't help me much, sadly. There's no entry about a failed unmount.

slick3371 wrote:

I have been having the same issue. From what I've experienced, the issue seems to happen only when either Plymouth is installed, or when /etc/mkinitcpio.conf contains the plymouth hook. I also cannot find this error in journalctl.

Yep, same here. If I remove plymouth entirely from my system, the PCs shut down normally. Perhaps that's a Plymouth bug?

Also, sorry for not replying, I accidentaly turned off notifications for this topic.

DAC324 · 2022-07-30 10:35:39

This is random error because of Nvidia driver (apparently it never does that without Nvidia driver installed).

Solution:

Create a script with the following contents

#!/bin/sh
# Remove all Nvidia modules on shutdown
# to avoid errors like
# [35509.312925] sd-umoun[56020]: Failed to unmount /oldroot: Device or resource busy
# [35509.317505] sd-umoun[56021]: Failed to unmount /oldroot/sys: Device or resource busy
# [35509.322349] shutdown[1]: Failed to finalize file systems, ignoring.
#
for MODULE in nvidia_drm nvidia_modeset nvidia_uvm nvidia
   do
# we will have to check if the modules are still loaded because they aren't always
       if lsmod | grep "$MODULE" &> /dev/null ; then
          rmmod $MODULE
       fi
   done

Name this script, for example, `nvidia.shutdown`, make it executable as usual and place it in `/usr/lib/systemd/system-shutdown`.

Last edited by DAC324 (2022-07-30 10:36:14)

Hello_User · 2022-08-03 21:20:07

DAC324 wrote:

This is random error because of Nvidia driver (apparently it never does that without Nvidia driver installed).

This is false. I'm on a laptop with only an intel iGPU and I'm experiencing the exact same issue. As far as I can tell, it's also started happening to me after installing and configuring plymouth.

DAC324 · 2022-08-05 21:02:27

That's interesting.
What I guess is that Plymouth might interfere with intel graphics driver unloading.
To verify if that's really the case, I'd change the Nvidia module names for the Intel ones you use, in the script I proposed.
Then, I'd install it as a shutdown script as described, and test it.

Arch Linux

#1 2022-03-21 09:29:52

/oldroot fails to unmount, shutdown unaffected

#2 2022-03-21 13:04:33

Re: /oldroot fails to unmount, shutdown unaffected

#3 2022-03-21 13:33:55

Re: /oldroot fails to unmount, shutdown unaffected

#4 2022-03-21 13:35:38

Re: /oldroot fails to unmount, shutdown unaffected

#5 2022-03-21 13:37:44

Re: /oldroot fails to unmount, shutdown unaffected

#6 2022-03-21 14:12:59

Re: /oldroot fails to unmount, shutdown unaffected

#7 2022-03-22 23:05:36

Re: /oldroot fails to unmount, shutdown unaffected

#8 2022-05-04 06:30:03

Re: /oldroot fails to unmount, shutdown unaffected

#9 2022-07-30 10:35:39

Re: /oldroot fails to unmount, shutdown unaffected

#10 2022-08-03 21:20:07

Re: /oldroot fails to unmount, shutdown unaffected

#11 2022-08-05 21:02:27

Re: /oldroot fails to unmount, shutdown unaffected

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