I have performed a rsync between two folders:

rsync -avzh /mnt/folder1 /mnt/folder2

(folder1 was /dev/sdb and folder2 was /dev/sdc, both ext4 partitions)

Then I have unmounted folder1 and I made a mistake and I mounted /dev/sdc directly over /mnt with:

mount /dev/sdc /mnt

When in fact I wanted to mount /dev/sdc over /mnt/folder1

Now I am not able to umount /mnt:

umount /mnt/
umount: /mnt/: target is busy
    (In some cases useful info about processes that
     use the device is found by lsof(8) or fuser(1).)

How can I fix this?

2 Answers 2


This is, to prevent data loss !

Run the following command, to see what process prevents unmounting. I am assumimg, that you skipped the partition on the dev to type less:

lsof | grep '/dev/sdc'

Close your work or end the given processes and unmount again. You cal also see, what files are still open with:

fuser -u /mnt/

Whereas the following command will kill all processes itself and probaply result in data loss:

fuser -km /mnt

Or show it as unmounted and let it automatically unmount, when the processes have finished:

umount -l /mnt

Check so that there isn't any process using the mountpoint, like your own shell for example.

If that doesn't do it

lsof |grep /mnt/

can help you pinpoint what's using the mountpoint.

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