--- a/jdk/src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedSynchronizer.java	Wed Nov 18 14:51:10 2015 +0100
+++ b/jdk/src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedSynchronizer.java	Fri Dec 11 09:08:12 2015 -0800
@@ -39,6 +39,7 @@
 import java.util.Collection;
 import java.util.Date;
 import java.util.concurrent.TimeUnit;
+import jdk.internal.vm.annotation.ReservedStackAccess;
 
 /**
  * Provides a framework for implementing blocking locks and related
@@ -886,6 +887,7 @@
      * @param arg the acquire argument
      * @return {@code true} if interrupted while waiting
      */
+    @ReservedStackAccess
     final boolean acquireQueued(final Node node, int arg) {
         try {
             boolean interrupted = false;
@@ -1218,6 +1220,7 @@
      *        {@link #tryAcquire} but is otherwise uninterpreted and
      *        can represent anything you like.
      */
+    @ReservedStackAccess
     public final void acquire(int arg) {
         if (!tryAcquire(arg) &&
             acquireQueued(addWaiter(Node.EXCLUSIVE), arg))
@@ -1281,6 +1284,7 @@
      *        can represent anything you like.
      * @return the value returned from {@link #tryRelease}
      */
+    @ReservedStackAccess
     public final boolean release(int arg) {
         if (tryRelease(arg)) {
             Node h = head;
@@ -1361,6 +1365,7 @@
      *        and can represent anything you like.
      * @return the value returned from {@link #tryReleaseShared}
      */
+    @ReservedStackAccess
     public final boolean releaseShared(int arg) {
         if (tryReleaseShared(arg)) {
             doReleaseShared();

--- a/jdk/src/java.base/share/classes/java/util/concurrent/locks/ReentrantLock.java	Wed Nov 18 14:51:10 2015 +0100
+++ b/jdk/src/java.base/share/classes/java/util/concurrent/locks/ReentrantLock.java	Fri Dec 11 09:08:12 2015 -0800
@@ -37,6 +37,7 @@
 
 import java.util.Collection;
 import java.util.concurrent.TimeUnit;
+import jdk.internal.vm.annotation.ReservedStackAccess;
 
 /**
  * A reentrant mutual exclusion {@link Lock} with the same basic
@@ -127,6 +128,7 @@
          * Performs non-fair tryLock.  tryAcquire is implemented in
          * subclasses, but both need nonfair try for trylock method.
          */
+        @ReservedStackAccess
         final boolean nonfairTryAcquire(int acquires) {
             final Thread current = Thread.currentThread();
             int c = getState();
@@ -146,6 +148,7 @@
             return false;
         }
 
+        @ReservedStackAccess
         protected final boolean tryRelease(int releases) {
             int c = getState() - releases;
             if (Thread.currentThread() != getExclusiveOwnerThread())
@@ -203,6 +206,7 @@
          * Performs lock.  Try immediate barge, backing up to normal
          * acquire on failure.
          */
+        @ReservedStackAccess
         final void lock() {
             if (compareAndSetState(0, 1))
                 setExclusiveOwnerThread(Thread.currentThread());
@@ -229,6 +233,7 @@
          * Fair version of tryAcquire.  Don't grant access unless
          * recursive call or no waiters or is first.
          */
+        @ReservedStackAccess
         protected final boolean tryAcquire(int acquires) {
             final Thread current = Thread.currentThread();
             int c = getState();

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.base/share/classes/jdk/internal/vm/annotation/ReservedStackAccess.java	Fri Dec 11 09:08:12 2015 -0800
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.internal.vm.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * <p>An annotation expressing that a method is especially sensitive
+ * to stack overflows. This is a hint the JVM can use to grant access to
+ * extra stack space when executing this code if such feature is supported
+ * by the JVM. The JVM is free to ignore this annotation.
+ *
+ * A possible way for the JVM to improve the execution context for methods
+ * with this annotation is to reserve part of the thread's execution stack
+ * for them. Access to this section of the stack would be denied by default
+ * but could be granted if the JVM detects a possible stack overflow and
+ * the thread's call stack includes at least one annotated method. Even if
+ * access to this reserved area has been granted, the JVM might decide to
+ * throw a delayed StackOverflowError when the thread exits the annotated
+ * method.
+ *
+ * @since 1.9
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.METHOD, ElementType.CONSTRUCTOR})
+public @interface ReservedStackAccess { }