umount: target is busy / Device or resource busy — how to fix

umount: /mnt/data: target is busy.
rm: cannot remove '/mnt/data': Device or resource busy
mount: /mnt/usb: /dev/sdb1 already mounted or mount point busy.

Quick fix: Find the user: sudo fuser -vm /mnt/data or sudo lsof +f -- /mnt/data, then cd out of it and stop or kill those processes, and run sudo umount /mnt/data. Last resort: sudo umount -l /mnt/data (lazy detach). For rm errors, the path is a mount point: unmount it first.

What it means

EBUSY means the kernel can't complete the operation while something else holds a reference. For umount, any open file, current working directory, memory-mapped file, nested mount, loop device or swap file on that filesystem keeps it busy.

Fix 1: find and stop what's using it

sudo fuser -vm /mnt/data          # -m: everything on that filesystem
sudo lsof +f -- /mnt/data         # open files on the filesystem

fuser shows the access type: c = current directory, f = open file, m = mmap, e = running executable.

The usual culprit is your own shell:

pwd          # inside /mnt/data? then:
cd ~
sudo umount /mnt/data

Stop services cleanly (sudo systemctl stop myapp) rather than killing them. To kill all processes using the mount (careful):

sudo fuser -km /mnt/data

Fix 2: nested mounts

If something is mounted under the target, unmount that first, or unmount the whole tree:

findmnt -R /mnt/data
sudo umount -R /mnt/data

Bind mounts, chroots (/mnt/chroot/proc, /dev, /sys) and Docker volumes often leave nested mounts behind.

Fix 3: swap, loop devices, LVM, RAID

• Swap file on the filesystem: sudo swapoff /mnt/data/swapfile.
• Loop devices backed by files there: losetup -a, then sudo losetup -d /dev/loop0.
• Wiping or repartitioning a disk fails with "Device or resource busy" when it holds an active LVM volume group or RAID array: sudo vgchange -an <vg> or sudo mdadm --stop /dev/md0. lsblk shows what sits on the device.

Fix 4: lazy unmount (last resort)

sudo umount -l /mnt/data

This detaches the mount point immediately and finishes cleanup when the last user closes it. Processes still using it keep working on the old filesystem, so don't unplug the device until they are gone. For a dead NFS server, use sudo umount -f -l /mnt/nfs.

Fix 5: rm: cannot remove ... Device or resource busy

The directory is a mount point (often inside Docker containers: /etc/hosts, /etc/resolv.conf and volume paths are bind mounts). Check with findmnt /path or mountpoint /path. Unmount it first on the host; inside a container, change the volume configuration instead of deleting the file.

Fix 6: mount: ... already mounted or mount point busy

The device is already mounted somewhere else or used by something (swap, RAID, LVM, or an automounter):

findmnt /dev/sdb1
lsblk -f /dev/sdb

Unmount it from the other location first, or mount the right partition (/dev/sdb1 vs /dev/sdb).

Desktop file managers and indexers

GNOME/KDE file managers, tracker-miner, baloo, antivirus and backup tools often have files open on USB drives. Close windows showing the drive, or eject from the file manager, which handles this for you.

Last updated 2026-11-07.