diff --git a/hadoop-yarn-project/CHANGES.txt b/hadoop-yarn-project/CHANGES.txt
index 5f92760afa4..caa1e12acce 100644
--- a/hadoop-yarn-project/CHANGES.txt
+++ b/hadoop-yarn-project/CHANGES.txt
@@ -208,6 +208,9 @@ Release 2.5.0 - UNRELEASED
     YARN-2121. Fixed NPE handling in Timeline Server's TimelineAuthenticator.
     (Zhijie Shen via vinodkv)
 
+    YARN-2128. FairScheduler: Incorrect calculation of amResource usage.
+    (Wei Yan via kasha)
+
 Release 2.4.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/SchedulerApplicationAttempt.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/SchedulerApplicationAttempt.java
index cce2e46cadd..ed41a6b30ce 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/SchedulerApplicationAttempt.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/SchedulerApplicationAttempt.java
@@ -79,6 +79,7 @@ public class SchedulerApplicationAttempt {
   protected Resource currentConsumption = Resource.newInstance(0, 0);
   private Resource amResource;
   private boolean unmanagedAM = true;
+  private boolean amRunning = false;
 
   protected List<RMContainer> newlyAllocatedContainers = 
       new ArrayList<RMContainer>();
@@ -110,7 +111,6 @@ public class SchedulerApplicationAttempt {
             activeUsersManager);
     this.queue = queue;
 
-
     if (rmContext != null && rmContext.getRMApps() != null &&
         rmContext.getRMApps()
             .containsKey(applicationAttemptId.getApplicationId())) {
@@ -118,7 +118,6 @@ public class SchedulerApplicationAttempt {
           rmContext.getRMApps().get(applicationAttemptId.getApplicationId())
               .getApplicationSubmissionContext();
       if (appSubmissionContext != null) {
-        amResource = appSubmissionContext.getResource();
         unmanagedAM = appSubmissionContext.getUnmanagedAM();
       }
     }
@@ -188,6 +187,18 @@ public class SchedulerApplicationAttempt {
     return amResource;
   }
 
+  public void setAMResource(Resource amResource) {
+    this.amResource = amResource;
+  }
+
+  public boolean isAmRunning() {
+    return amRunning;
+  }
+
+  public void setAmRunning(boolean bool) {
+    amRunning = bool;
+  }
+
   public boolean getUnmanagedAM() {
     return unmanagedAM;
   }
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/AppSchedulable.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/AppSchedulable.java
index 32edc8a2641..a1704cdbd2b 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/AppSchedulable.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/AppSchedulable.java
@@ -271,6 +271,7 @@ public class AppSchedulable extends Schedulable {
       if (app.getLiveContainers().size() == 1 &&
           !app.getUnmanagedAM()) {
         queue.addAMResourceUsage(container.getResource());
+        app.setAmRunning(true);
       }
 
       return container.getResource();
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSLeafQueue.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSLeafQueue.java
index cecfbfc8e1d..8634f0dd138 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSLeafQueue.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSLeafQueue.java
@@ -91,7 +91,7 @@ public class FSLeafQueue extends FSQueue {
   public boolean removeApp(FSSchedulerApp app) {
     if (runnableAppScheds.remove(app.getAppSchedulable())) {
       // Update AM resource usage
-      if (app.getAMResource() != null) {
+      if (app.isAmRunning() && app.getAMResource() != null) {
         Resources.subtractFrom(amResourceUsage, app.getAMResource());
       }
       return true;
@@ -153,6 +153,10 @@ public class FSLeafQueue extends FSQueue {
     return usage;
   }
 
+  public Resource getAmResourceUsage() {
+    return amResourceUsage;
+  }
+
   @Override
   public void updateDemand() {
     // Compute demand by iterating through apps in the queue
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java
index 1b7011a88ca..5725f8c383b 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java
@@ -836,6 +836,12 @@ public class FairScheduler extends
     SchedulerUtils.normalizeRequests(ask, new DominantResourceCalculator(),
         clusterResource, minimumAllocation, maximumAllocation, incrAllocation);
 
+    // Set amResource for this app
+    if (!application.getUnmanagedAM() && ask.size() == 1
+        && application.getLiveContainers().isEmpty()) {
+      application.setAMResource(ask.get(0).getCapability());
+    }
+
     // Release containers
     for (ContainerId releasedContainerId : release) {
       RMContainer rmContainer = getRMContainer(releasedContainerId);
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/TestFairScheduler.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/TestFairScheduler.java
index b650d8cbb82..9d8b1d117d0 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/TestFairScheduler.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/TestFairScheduler.java
@@ -2328,12 +2328,13 @@ public class TestFairScheduler extends FairSchedulerTestBase {
     scheduler.handle(nodeEvent);
     scheduler.update();
 
+    FSLeafQueue queue1 = scheduler.getQueueManager().getLeafQueue("queue1", true);
     assertEquals("Queue queue1's fair share should be 10240",
-        10240, scheduler.getQueueManager().getLeafQueue("queue1", true)
-            .getFairShare().getMemory());
+        10240, queue1.getFairShare().getMemory());
 
     Resource amResource1 = Resource.newInstance(1024, 1);
     Resource amResource2 = Resource.newInstance(2048, 2);
+    Resource amResource3 = Resource.newInstance(1860, 2);
     int amPriority = RMAppAttemptImpl.AM_CONTAINER_PRIORITY.getPriority();
     // Exceeds no limits
     ApplicationAttemptId attId1 = createAppAttemptId(1, 1);
@@ -2346,6 +2347,8 @@ public class TestFairScheduler extends FairSchedulerTestBase {
         1024, app1.getAMResource().getMemory());
     assertEquals("Application1's AM should be running",
         1, app1.getLiveContainers().size());
+    assertEquals("Queue1's AM resource usage should be 1024 MB memory",
+        1024, queue1.getAmResourceUsage().getMemory());
 
     // Exceeds no limits
     ApplicationAttemptId attId2 = createAppAttemptId(2, 1);
@@ -2358,6 +2361,8 @@ public class TestFairScheduler extends FairSchedulerTestBase {
         1024, app2.getAMResource().getMemory());
     assertEquals("Application2's AM should be running",
         1, app2.getLiveContainers().size());
+    assertEquals("Queue1's AM resource usage should be 2048 MB memory",
+        2048, queue1.getAmResourceUsage().getMemory());
 
     // Exceeds queue limit
     ApplicationAttemptId attId3 = createAppAttemptId(3, 1);
@@ -2370,6 +2375,8 @@ public class TestFairScheduler extends FairSchedulerTestBase {
         1024, app3.getAMResource().getMemory());
     assertEquals("Application3's AM should not be running",
         0, app3.getLiveContainers().size());
+    assertEquals("Queue1's AM resource usage should be 2048 MB memory",
+        2048, queue1.getAmResourceUsage().getMemory());
 
     // Still can run non-AM container
     createSchedulingRequestExistingApplication(1024, 1, attId1);
@@ -2377,6 +2384,8 @@ public class TestFairScheduler extends FairSchedulerTestBase {
     scheduler.handle(updateEvent);
     assertEquals("Application1 should have two running containers",
         2, app1.getLiveContainers().size());
+    assertEquals("Queue1's AM resource usage should be 2048 MB memory",
+        2048, queue1.getAmResourceUsage().getMemory());
 
     // Remove app1, app3's AM should become running
     AppAttemptRemovedSchedulerEvent appRemovedEvent1 =
@@ -2388,6 +2397,8 @@ public class TestFairScheduler extends FairSchedulerTestBase {
         0, app1.getLiveContainers().size());
     assertEquals("Application3's AM should be running",
         1, app3.getLiveContainers().size());
+    assertEquals("Queue1's AM resource usage should be 2048 MB memory",
+        2048, queue1.getAmResourceUsage().getMemory());
 
     // Exceeds queue limit
     ApplicationAttemptId attId4 = createAppAttemptId(4, 1);
@@ -2400,8 +2411,35 @@ public class TestFairScheduler extends FairSchedulerTestBase {
         2048, app4.getAMResource().getMemory());
     assertEquals("Application4's AM should not be running",
         0, app4.getLiveContainers().size());
+    assertEquals("Queue1's AM resource usage should be 2048 MB memory",
+        2048, queue1.getAmResourceUsage().getMemory());
 
-    // Remove app2 and app3, app4's AM should become running
+    // Exceeds queue limit
+    ApplicationAttemptId attId5 = createAppAttemptId(5, 1);
+    createApplicationWithAMResource(attId5, "queue1", "user1", amResource2);
+    createSchedulingRequestExistingApplication(2048, 2, amPriority, attId5);
+    FSSchedulerApp app5 = scheduler.getSchedulerApp(attId5);
+    scheduler.update();
+    scheduler.handle(updateEvent);
+    assertEquals("Application5's AM requests 2048 MB memory",
+        2048, app5.getAMResource().getMemory());
+    assertEquals("Application5's AM should not be running",
+        0, app5.getLiveContainers().size());
+    assertEquals("Queue1's AM resource usage should be 2048 MB memory",
+        2048, queue1.getAmResourceUsage().getMemory());
+
+    // Remove un-running app doesn't affect others
+    AppAttemptRemovedSchedulerEvent appRemovedEvent4 =
+        new AppAttemptRemovedSchedulerEvent(attId4, RMAppAttemptState.KILLED, false);
+    scheduler.handle(appRemovedEvent4);
+    scheduler.update();
+    scheduler.handle(updateEvent);
+    assertEquals("Application5's AM should not be running",
+        0, app5.getLiveContainers().size());
+    assertEquals("Queue1's AM resource usage should be 2048 MB memory",
+        2048, queue1.getAmResourceUsage().getMemory());
+
+    // Remove app2 and app3, app5's AM should become running
     AppAttemptRemovedSchedulerEvent appRemovedEvent2 =
         new AppAttemptRemovedSchedulerEvent(attId2, RMAppAttemptState.FINISHED, false);
     AppAttemptRemovedSchedulerEvent appRemovedEvent3 =
@@ -2414,8 +2452,35 @@ public class TestFairScheduler extends FairSchedulerTestBase {
         0, app2.getLiveContainers().size());
     assertEquals("Application3's AM should be finished",
         0, app3.getLiveContainers().size());
-    assertEquals("Application4's AM should be running",
-        1, app4.getLiveContainers().size());
+    assertEquals("Application5's AM should be running",
+        1, app5.getLiveContainers().size());
+    assertEquals("Queue1's AM resource usage should be 2048 MB memory",
+        2048, queue1.getAmResourceUsage().getMemory());
+
+    // Check amResource normalization
+    ApplicationAttemptId attId6 = createAppAttemptId(6, 1);
+    createApplicationWithAMResource(attId6, "queue1", "user1", amResource3);
+    createSchedulingRequestExistingApplication(1860, 2, amPriority, attId6);
+    FSSchedulerApp app6 = scheduler.getSchedulerApp(attId6);
+    scheduler.update();
+    scheduler.handle(updateEvent);
+    assertEquals("Application6's AM should not be running",
+        0, app6.getLiveContainers().size());
+    assertEquals("Application6's AM requests 2048 MB memory",
+        2048, app6.getAMResource().getMemory());
+    assertEquals("Queue1's AM resource usage should be 2048 MB memory",
+        2048, queue1.getAmResourceUsage().getMemory());
+
+    // Remove all apps
+    AppAttemptRemovedSchedulerEvent appRemovedEvent5 =
+        new AppAttemptRemovedSchedulerEvent(attId5, RMAppAttemptState.FINISHED, false);
+    AppAttemptRemovedSchedulerEvent appRemovedEvent6 =
+        new AppAttemptRemovedSchedulerEvent(attId6, RMAppAttemptState.FINISHED, false);
+    scheduler.handle(appRemovedEvent5);
+    scheduler.handle(appRemovedEvent6);
+    scheduler.update();
+    assertEquals("Queue1's AM resource usage should be 0",
+        0, queue1.getAmResourceUsage().getMemory());
   }
 
   @Test