diff --git a/man2/futex.2 b/man2/futex.2
index e69813f2f..d6881c095 100644
--- a/man2/futex.2
+++ b/man2/futex.2
@@ -12,20 +12,6 @@
 .\" Modified 2004-06-17 mtk
 .\" Modified 2004-10-07 aeb, added FUTEX_REQUEUE, FUTEX_CMP_REQUEUE
 .\"
-.\" 2.6.18 adds (Ingo Molnar) priority inheritance support:
-.\" FUTEX_LOCK_PI, FUTEX_UNLOCK_PI, and FUTEX_TRYLOCK_PI.  These need
-.\" to be documented in the manual page.  Probably there is sufficient
-.\" material in the kernel source file Documentation/pi-futex.txt.
-.\"	commit c87e2837be82df479a6bae9f155c43516d2feebc
-.\"	Author: Ingo Molnar <mingo@elte.hu>
-.\"	Date:   Tue Jun 27 02:54:58 2006 -0700
-.\"
-.\"	commit e2970f2fb6950183a34e8545faa093eb49d186e1
-.\"	Author: Ingo Molnar <mingo@elte.hu>
-.\"	Date:   Tue Jun 27 02:54:47 2006 -0700
-.\"
-.\"	See Documentation/pi-futex.txt
-.\"
 .\" 2.6.31 adds FUTEX_WAIT_REQUEUE_PI, FUTEX_CMP_REQUEUE_PI
 .\"	commit 52400ba946759af28442dee6265c5c0180ac7122
 .\"	Author: Darren Hart <dvhltc@us.ibm.com>
@@ -704,7 +690,23 @@ User space cannot handle this race free.
 .BR FUTEX_UNLOCK_PI " (since Linux 2.6.18)"
 .\" commit c87e2837be82df479a6bae9f155c43516d2feebc
 .\" FIXME to complete
-[As yet undocumented]
+This operation wakes the top priority waiter which is waiting in
+.B FUTEX_LOCK_PI
+on the futex address provided by the
+.I uaddr
+argument.
+
+This is called when the user space value at
+.I uaddr
+cannot be changed atomically from a TID (of the owner) to 0.
+
+The
+.IR uaddr2 ,
+.IR val ,
+.IR timeout ,
+and
+.IR val3
+are ignored.
 .TP
 .BR FUTEX_CMP_REQUEUE_PI " (since Linux 2.6.31)"
 .\" commit 52400ba946759af28442dee6265c5c0180ac7122