diff --git a/man2/mmap.2 b/man2/mmap.2
index bf7f449e1..503df4caf 100644
--- a/man2/mmap.2
+++ b/man2/mmap.2
@@ -261,8 +261,19 @@ can be discovered by listing the subdirectories in
 .IR /sys/kernel/mm/hugepages .
 .TP
 .BR MAP_LOCKED " (since Linux 2.5.37)"
-Lock the pages of the mapped region into memory in the manner of
+Mark the mmaped region to be locked in the same way as
 .BR mlock (2).
+This implementation will try to populate (prefault) the whole range but
+the mmap call doesn't fail with
+.B ENOMEM
+if this fails. Therefore major faults might happen later on. So the semantic
+is not as strong as
+.BR mlock (2).
+.BR mmap (2)
++
+.BR mlock (2)
+should be used when major faults are not acceptable after the initialization
+of the mapping.
 This flag is ignored in older kernels.
 .\" If set, the mapped pages will not be swapped out.
 .TP