[PATCH 3/4] proc.5: Document the proc files for the user, mount, and pid namespaces.

[ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman)]

Signed-off-by: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
---
 man5/proc.5 |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 52 insertions(+), 0 deletions(-)

diff --git a/man5/proc.5 b/man5/proc.5
index 840480d..eb612b9 100644
--- a/man5/proc.5
+++ b/man5/proc.5
@@ -581,6 +581,58 @@ 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/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/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]/numa_maps " (since Linux 2.6.14)"
 See
 .BR numa (7).
-- 
1.7.5.4