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