How to unmount a formerly chroot'd filesystem?

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http://unix.stackexchange.com – I'm using a rescue-live-system (similar to a live-cd) to fix some issues with my Debian server, like that: # mkdir -p /mnt/rescue # mount /dev/md2 /mnt/rescue # mount --bind /dev /mnt/rescue/dev/ # mount --bind /proc /mnt/rescue/proc/ # mount --bind /sys /mnt/rescue/sys/ Now I can chroot to /mnt/rescue - but after I'm done, how to unmount the filesystem again? umount: /mnt/rescue: target is busy. (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1)) I guess it's because dev, proc and sys are bound to the mounted file system. But it's not (HowTos)