pagemap: document KPF_KSM and show it in page-types

It indicates to the system admin that processes mapping such pages may be
eating less physical memory than the reported numbers by legacy tools.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Acked-by: Chris Wright <chrisw@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 6 insertions, 0 deletions

diff --git a/Documentation/vm/page-types.c b/Documentation/vm/page-types.c
index 87f57228f56e..9899fa239eed 100644
--- a/Documentation/vm/page-types.c
+++ b/Documentation/vm/page-types.c
@@ -71,6 +71,7 @@
 #define KPF_UNEVICTABLE         18
 #define KPF_HWPOISON            19
 #define KPF_NOPAGE              20
+#define KPF_KSM                 21
 
 /* [32-] kernel hacking assistances */
 #define KPF_RESERVED            32
@@ -119,6 +120,7 @@ static char *page_flag_names[] = {
         [KPF_UNEVICTABLE]       = "u:unevictable",
         [KPF_HWPOISON]          = "X:hwpoison",
         [KPF_NOPAGE]            = "n:nopage",
+        [KPF_KSM]               = "x:ksm",
 
         [KPF_RESERVED]          = "r:reserved",
         [KPF_MLOCKED]           = "m:mlocked",
diff --git a/Documentation/vm/pagemap.txt b/Documentation/vm/pagemap.txt
index 2fdd84a19109..df09b9650a81 100644
--- a/Documentation/vm/pagemap.txt
+++ b/Documentation/vm/pagemap.txt
@@ -59,6 +59,7 @@ There are three components to pagemap:
     18. UNEVICTABLE
     19. HWPOISON
     20. NOPAGE
+    21. KSM
 
 Short descriptions to the page flags:
 
@@ -93,6 +94,9 @@ Short descriptions to the page flags:
 20. NOPAGE
     no page frame exists at the requested address
 
+21. KSM
+    identical memory pages dynamically shared between one or more processes
+
     [IO related page flags]
  1. ERROR     IO error occurred
  3. UPTODATE  page has up-to-date data