can't umount /mnt because /mnt/dev is busy

LonelyPyxel · 2019-01-03 14:21:59

Hello everyone.
I am installing Arch Linux on an old laptop and I have ran into an error.
After exiting from the new system, I cannot unmount /mnt.
When I run

umount -R /mnt

, the following is output:

umount: /mnt/dev: target is busy

If I try to chroot to the new system, I get the following error:

 mount: /mnt/dev: udev already mounted on /mnt/dev.
==> ERROR: failed to setup chroot /mnt

I checked each tty and none were using the mount.
I ran

fuser -vm /mnt

, and I got the following:

        USER                    PID                 ACCESS         COMMAND
        root                       kernel              mount              /mnt

I am using gpt and my partitions are as follows:
/dev/sda1 200M, for boot
/dev/sda2 9G, swap
/dev/sda3 30G, for /
/dev/sda4 659G, for /home
/dev/sda5 2M, BIOS boot

One note is that after I created the filesystems and swap, I went back and deleted /dev/sda4, created a new partition in the same place but a little smaller, and then said NO when asked if I would like remove the signature. I then created /dev/sda5 and set it to BIOS boot type. (so that I was able to install grub). Since then, I haven't done anything related to partitioning or mounting.
Any help would be appreciated.

Last edited by LonelyPyxel (2019-01-03 14:26:51)

schard · 2019-01-03 14:25:46

You are probably using the respective mount point as working directory within some shell session.

Trilby · 2019-01-03 14:34:58

LonelyPyxel wrote:

after I created the filesystems and swap, I went back and deleted /dev/sda4, created a new partition in the same place but a little smaller

Did you do all of this before you chrooted? Or did you do any of these steps from within the chroot?

LonelyPyxel · 2019-01-03 20:54:45

Trilby wrote:

LonelyPyxel wrote:
after I created the filesystems and swap, I went back and deleted /dev/sda4, created a new partition in the same place but a little smaller
Did you do all of this before you chrooted? Or did you do any of these steps from within the chroot?

I did these steps AFTER I chrooted.

Another note is, when I run

fuser -mv /mnt/dev

(as opposed to fuser -mv /mnt, like in OP)
I get all this.

Trilby · 2019-01-03 21:00:54

Those steps should have been done before chrooting. This may likely explain the problem as you would have mounted devices within the chroot. Honestly, I'm not 100% sure what I'd expect to happen in such a case, but the error message in your first post seems like a plausible and reasonable result of those conditions.

Arch Linux

#1 2019-01-03 14:21:59

can't umount /mnt because /mnt/dev is busy

#2 2019-01-03 14:25:46

Re: can't umount /mnt because /mnt/dev is busy

#3 2019-01-03 14:34:58

Re: can't umount /mnt because /mnt/dev is busy

#4 2019-01-03 20:54:45

Re: can't umount /mnt because /mnt/dev is busy

#5 2019-01-03 21:00:54

Re: can't umount /mnt because /mnt/dev is busy

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