Linux: Which process is causing "device busy" when doing umount?

Question

Linux: Which process is causing "device busy" when doing umount?

Solution 1

Look at the lsof command (list open files) -- it can tell you which processes are holding what open. Sometimes it's tricky but often something as simple as sudo lsof | grep (your device name here) could do it for you.

Solution 2

Just in case... sometimes happens that you are calling umount from the terminal, and your current directory belongs to the mounted filesystem.

Solution 3

You should use the fuser command.

Eg. fuser /dev/cdrom will return the pid(s) of the process using /dev/cdrom.

If you are trying to unmount, you can kill theses process using the -k switch (see man fuser).

Solution 4

Check for open loop devices mapped to a file on the filesystem with "losetup -a". They wont show up with either lsof or fuser.

Solution 5

Also check /etc/exports. If you are exporting paths within the mountpoint via NFS, it will give this error when trying to unmount and nothing will show up in fuser or lsof.

View more solutions