Trying to use a chrooted system via
mount -B stage3 gentoo
mount -t sysfs none gentoo/sys
mount -t proc none gentoo/proc
mount -R /dev gentoo/dev
mount --make-rslave gentoo/dev
unshare --fork chroot ...
a NFS share is mounted on /mnt/temp/dir (and other shares are mounted in subdirectories),
I umount everything there but supposedly, it doesn't work well (maybe I start with umount /mnt/temp/...