diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 9f5481bdc5a43f942fb833f3131901249d2d5c50..d614a9b6a28048ecf879e96b3aada686ecadb6cb 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -696,7 +696,9 @@ swappiness
 
 This control is used to define how aggressive the kernel will swap
 memory pages.  Higher values will increase agressiveness, lower values
-decrease the amount of swap.
+decrease the amount of swap.  A value of 0 instructs the kernel not to
+initiate swap until the amount of free and file-backed pages is less
+than the high water mark in a zone.
 
 The default value is 60.