diff --git a/Documentation/vm/hwpoison.txt b/Documentation/vm/hwpoison.txt
index f454d3c..989e5af 100644
--- a/Documentation/vm/hwpoison.txt
+++ b/Documentation/vm/hwpoison.txt
@@ -123,6 +123,22 @@
 by block device major/minor.  -1U is the wildcard value.
 This should be only used for testing with artificial injection.
 
+corrupt-filter-memcg
+
+Limit injection to pages owned by memgroup. Specified by inode number
+of the memcg.
+
+Example:
+        mkdir /cgroup/hwpoison
+
+        usemem -m 100 -s 1000 &
+        echo `jobs -p` > /cgroup/hwpoison/tasks
+
+        memcg_ino=$(ls -id /cgroup/hwpoison | cut -f1 -d' ')
+        echo $memcg_ino > /debug/hwpoison/corrupt-filter-memcg
+
+        page-types -p `pidof init`   --hwpoison  # shall do nothing
+        page-types -p `pidof usemem` --hwpoison  # poison its pages
 
 corrupt-filter-flags-mask
 corrupt-filter-flags-value