+anymore.
+
+A system reboot would be expected in near future if you're going to use this
+option for network filesystem or local filesystem with submounts. The
+recommended use-case for \fBumount \-l\fR is to prevent hangs on shutdown due to
+an unreachable network share where a normal umount will hang due to a downed
+server or a network partition. Remounts of the share will not be possible.
+
+.TP
+.BR \-N , " \-\-namespace " \fIns
+Perform umount in the mount namespace specified by \fIns\fR.
+\fIns\fR is either PID of process running in that namespace
+or special file representing that namespace.
+.sp
+.BR umount (8)
+switches to the namespace when it reads /etc/fstab, writes /etc/mtab (or writes to /run/mount) and calls
+.BR umount (2)
+system call, otherwise it runs in the original namespace.
+It means that the target mount namespace does not have
+to contain any libraries or another requirements necessary to execute
+.BR umount (2)
+command.
+.sp
+See \fBmount_namespaces\fR(7) for more information.