proc.5: Document /proc/PID/ns/{user,pid,mnt}

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man5/proc.5 b/man5/proc.5
index 5ae58628fc7400f6a27b1d512020674a18664b2d..4c254eda715907c3a3203b5637af6bb719e8c85d 100644 (file)
--- a/man5/proc.5
+++ b/man5/proc.5
@@ -876,6 +876,23 @@ even if all processes in the namespace terminate.
 The file descriptor can be passed to
 .BR setns (2).
 .TP
+.IR /proc/[pid]/ns/mnt " (since Linux 3.8)"
+Bind mounting this file (see
+.BR mount (2))
+to somewhere else in the filesystem keeps
+the mount namespace of the process specified by
+.I pid
+alive even if all processes currently in the namespace terminate.
+
+Opening this file returns a file handle for the mount namespace
+of the process specified by
+.IR pid .
+As long as this file descriptor remains open,
+the mount namespace will remain alive,
+even if all processes in the namespace terminate.
+The file descriptor can be passed to
+.BR setns (2).
+.TP
 .IR /proc/[pid]/ns/net " (since Linux 3.0)"
 Bind mounting this file (see
 .BR mount (2))
@@ -893,6 +910,40 @@ even if all processes in the namespace terminate.
 The file descriptor can be passed to
 .BR setns (2).
 .TP
+.IR /proc/[pid]/ns/pid " (since Linux 3.8)"
+Bind mounting this file (see
+.BR mount (2))
+to somewhere else in the filesystem keeps
+the PID namespace of the process specified by
+.I pid
+alive even if all processes currently in the namespace terminate.
+
+Opening this file returns a file handle for the PID namespace
+of the process specified by
+.IR pid .
+As long as this file descriptor remains open,
+the PID namespace will remain alive,
+even if all processes in the namespace terminate.
+The file descriptor can be passed to
+.BR setns (2).
+.TP
+.IR /proc/[pid]/ns/user " (since Linux 3.8)"
+Bind mounting this file (see
+.BR mount (2))
+to somewhere else in the filesystem keeps
+the user namespace of the process specified by
+.I pid
+alive even if all processes currently in the namespace terminate.
+
+Opening this file returns a file handle for the user namespace
+of the process specified by
+.IR pid .
+As long as this file descriptor remains open,
+the user namespace will remain alive,
+even if all processes in the namespace terminate.
+The file descriptor can be passed to
+.BR setns (2).
+.TP
 .IR /proc/[pid]/ns/uts " (since Linux 3.0)"
 Bind mounting this file (see
 .BR mount (2))
@@ -909,6 +960,7 @@ the UTS namespace will remain alive,
 even if all processes in the namespace terminate.
 The file descriptor can be passed to
 .BR setns (2).
+
 .TP
 .IR /proc/[pid]/numa_maps " (since Linux 2.6.14)"
 See