diff --git a/man2/mmap.2 b/man2/mmap.2
index 59f6fe8d0..7fe92236b 100644
--- a/man2/mmap.2
+++ b/man2/mmap.2
@@ -232,6 +232,34 @@ See the Linux kernel source file
 .I Documentation/vm/hugetlbpage.txt
 for further information.
 .TP
+.BR MAP_HUGE_2MB ", " MAP_HUGE_1GB " (since Linux 3.8)"
+.\" See https://lwn.net/Articles/533499/
+Used in conjunction with
+.B MAP_HUGETLB
+to select alternative hugetlb page sizes (respectively, 2 MB and 1 GB)
+on systems that support multiple hugetlb page sizes.
+
+More generally, the desired huge page size can be configured by encoding
+the base-2 logarithm of the desired page size in the six bits at the offset
+.BR MAP_HUGE_SHIFT .
+(A value of zero in this bit field provides the default huge page size;
+the default huge page size can be discovered vie the
+.I Hugepagesize
+field exposed by
+.IR /proc/meminfo .)
+Thus, the above two constants are defined as:
+
+.nf
+.in +4n
+#define MAP_HUGE_2MB    (21 << MAP_HUGE_SHIFT)
+#define MAP_HUGE_1GB    (30 << MAP_HUGE_SHIFT)
+.in
+.fi
+
+The range of huge page sizes that are supported by the system
+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
 .BR mlock (2).