mm: smaps: export mlock information

Currently there is no way to find whether a process has locked its pages
in memory or not.  And which of the memory regions are locked in memory.

Add a new field "Locked" to export this information via the smaps file.

Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 9471225..ef757fc 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -375,6 +375,7 @@
 Swap:                  0 kB
 KernelPageSize:        4 kB
 MMUPageSize:           4 kB
+Locked:              374 kB
 
 The first of these lines shows the same information as is displayed for the
 mapping in /proc/PID/maps.  The remaining lines show the size of the mapping
@@ -670,6 +671,8 @@
 
 > cat /proc/meminfo
 
+The "Locked" indicates whether the mapping is locked in memory or not.
+
 
 MemTotal:     16344972 kB
 MemFree:      13634064 kB