diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 28f0c46cd1..42814c19fd 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -687,6 +687,9 @@ Branch-2 ( Unreleased changes )
     HDFS-3856. TestHDFSServerPorts failure is causing surefire fork failure.
     (eli)
 
+    HDFS-3860. HeartbeatManager#Monitor may wrongly hold the writelock of
+    namesystem. (Jing Zhao via atm)
+
   BREAKDOWN OF HDFS-3042 SUBTASKS
 
     HDFS-2185. HDFS portion of ZK-based FailoverController (todd)
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/HeartbeatManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/HeartbeatManager.java
index 73926010a4..449619ced7 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/HeartbeatManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/HeartbeatManager.java
@@ -223,10 +223,10 @@ class HeartbeatManager implements DatanodeStatistics {
       if (!allAlive) {
         // acquire the fsnamesystem lock, and then remove the dead node.
         namesystem.writeLock();
-        if (namesystem.isInSafeMode()) {
-          return;
-        }
         try {
+          if (namesystem.isInSafeMode()) {
+            return;
+          }
           synchronized(this) {
             dm.removeDeadDatanode(dead);
           }