diff --git a/versioning/BRM/extentmap.cpp b/versioning/BRM/extentmap.cpp
index 29cb9fcb3..e59af8603 100644
--- a/versioning/BRM/extentmap.cpp
+++ b/versioning/BRM/extentmap.cpp
@@ -219,7 +219,9 @@ boost::mutex ExtentMapRBTreeImpl::fInstanceMutex;
 ExtentMapRBTreeImpl* ExtentMapRBTreeImpl::fInstance = nullptr;
 
 /*static*/
-ExtentMapRBTreeImpl* ExtentMapRBTreeImpl::makeExtentMapRBTreeImpl(unsigned key, off_t size, bool readOnly)
+ExtentMapRBTreeImpl* ExtentMapRBTreeImpl::makeExtentMapRBTreeImpl(unsigned key, off_t size, bool readOnly,
+                                                                  bool& emLocked,
+                                                                  const MasterSegmentTable* emSegTable)
 {
   boost::mutex::scoped_lock lk(fInstanceMutex);
 
@@ -227,7 +229,17 @@ ExtentMapRBTreeImpl* ExtentMapRBTreeImpl::makeExtentMapRBTreeImpl(unsigned key,
   {
     if (key != fInstance->fManagedShm.key())
     {
+      if (emSegTable)
+      {
+        emSegTable->getTable_upgrade(MasterSegmentTable::EMTable);
+        emLocked = true;
+      }
       fInstance->fManagedShm.reMapSegment();
+      if (emSegTable)
+      {
+        emLocked = false;
+        emSegTable->getTable_downgrade(MasterSegmentTable::EMTable);
+      }
     }
 
     return fInstance;
@@ -1941,7 +1953,11 @@ void ExtentMap::grabEMEntryTable(OPS op)
     }
     else
     {
-      fPExtMapRBTreeImpl = ExtentMapRBTreeImpl::makeExtentMapRBTreeImpl(fEMRBTreeShminfo->tableShmkey, 0);
+      const bool isReadOnly = false;
+      // The ternary sends EM segment table only if this grabEMEntryTable call
+      // is for a READ op to enable RWLock upgrade in case of a shmem segment remap.
+      fPExtMapRBTreeImpl = ExtentMapRBTreeImpl::makeExtentMapRBTreeImpl(
+          fEMRBTreeShminfo->tableShmkey, 0, isReadOnly, emLocked, op == READ ? &fMST : nullptr);
       ASSERT(fPExtMapRBTreeImpl);
 
       fExtentMapRBTree = fPExtMapRBTreeImpl->get();
@@ -2176,8 +2192,8 @@ void ExtentMap::growEMShmseg(size_t size)
     if (fEMRBTreeShminfo->tableShmkey == 0)
       fEMRBTreeShminfo->tableShmkey = newShmKey;
 
-    fPExtMapRBTreeImpl =
-        ExtentMapRBTreeImpl::makeExtentMapRBTreeImpl(fEMRBTreeShminfo->tableShmkey, allocSize, r_only);
+    fPExtMapRBTreeImpl = ExtentMapRBTreeImpl::makeExtentMapRBTreeImpl(fEMRBTreeShminfo->tableShmkey,
+                                                                      allocSize, r_only, emLocked);
   }
   else
   {
diff --git a/versioning/BRM/extentmap.h b/versioning/BRM/extentmap.h
index 5fc5d8cb9..0f16d3018 100644
--- a/versioning/BRM/extentmap.h
+++ b/versioning/BRM/extentmap.h
@@ -34,7 +34,7 @@
 #include <tr1/unordered_map>
 #include <mutex>
 
-//#define NDEBUG
+// #define NDEBUG
 #include <cassert>
 #include <boost/functional/hash.hpp>  //boost::hash
 #include <boost/interprocess/allocators/allocator.hpp>
@@ -253,7 +253,8 @@ class ExtentMapRBTreeImpl
  public:
   ~ExtentMapRBTreeImpl() = default;
 
-  static ExtentMapRBTreeImpl* makeExtentMapRBTreeImpl(unsigned key, off_t size, bool readOnly = false);
+  static ExtentMapRBTreeImpl* makeExtentMapRBTreeImpl(unsigned key, off_t size, bool readOnly, bool& emLocked,
+                                                      const MasterSegmentTable* emSegTable = nullptr);
 
   static void refreshShm()
   {