Index: openmp/libomptarget/src/device.h
===================================================================
--- openmp/libomptarget/src/device.h
+++ openmp/libomptarget/src/device.h
@@ -88,6 +88,10 @@
   }
 
   bool isRefCountInf() const { return RefCount == INFRefCount; }
+
+  std::string refCountToStr() const {
+    return isRefCountInf() ? "INF" : std::to_string(getRefCount());
+  }
 };
 
 typedef uintptr_t HstPtrBeginTy;
Index: openmp/libomptarget/src/device.cpp
===================================================================
--- openmp/libomptarget/src/device.cpp
+++ openmp/libomptarget/src/device.cpp
@@ -79,13 +79,14 @@
   HostDataToTargetTy newEntry((uintptr_t)HstPtrBegin /*HstPtrBase*/,
                               (uintptr_t)HstPtrBegin /*HstPtrBegin*/,
                               (uintptr_t)HstPtrBegin + Size /*HstPtrEnd*/,
-                              (uintptr_t)TgtPtrBegin /*TgtPtrBegin*/, nullptr,
-                              true /*IsRefCountINF*/);
+                              (uintptr_t)TgtPtrBegin /*TgtPtrBegin*/,
+                              nullptr /*Name*/, true /*IsRefCountINF*/);
 
   DP("Creating new map entry: HstBase=" DPxMOD ", HstBegin=" DPxMOD
-     ", HstEnd=" DPxMOD ", TgtBegin=" DPxMOD "\n",
+     ", HstEnd=" DPxMOD ", TgtBegin=" DPxMOD ", RefCount=%s\n",
      DPxPTR(newEntry.HstPtrBase), DPxPTR(newEntry.HstPtrBegin),
-     DPxPTR(newEntry.HstPtrEnd), DPxPTR(newEntry.TgtPtrBegin));
+     DPxPTR(newEntry.HstPtrEnd), DPxPTR(newEntry.TgtPtrBegin),
+     newEntry.refCountToStr().c_str());
   HostDataToTargetMap.insert(newEntry);
 
   DataMapMtx.unlock();
@@ -212,18 +213,20 @@
       ((lr.Flags.ExtendsBefore || lr.Flags.ExtendsAfter) && IsImplicit)) {
     auto &HT = *lr.Entry;
     IsNew = false;
-
-    if (UpdateRefCount)
+    const char *RefCountAction;
+    if (!UpdateRefCount)
+      RefCountAction = "update suppressed";
+    else {
+      RefCountAction = "incremented";
       HT.incRefCount();
-
+    }
     uintptr_t tp = HT.TgtPtrBegin + ((uintptr_t)HstPtrBegin - HT.HstPtrBegin);
     INFO(OMP_INFOTYPE_MAPPING_EXISTS, DeviceID,
          "Mapping exists%s with HstPtrBegin=" DPxMOD ", TgtPtrBegin=" DPxMOD
          ", "
-         "Size=%" PRId64 ",%s RefCount=%s, Name=%s\n",
+         "Size=%" PRId64 ", RefCount=%s (%s), Name=%s\n",
          (IsImplicit ? " (implicit)" : ""), DPxPTR(HstPtrBegin), DPxPTR(tp),
-         Size, (UpdateRefCount ? " updated" : ""),
-         HT.isRefCountInf() ? "INF" : std::to_string(HT.getRefCount()).c_str(),
+         Size, HT.refCountToStr().c_str(), RefCountAction,
          (HstPtrName) ? getNameFromMapping(HstPtrName).c_str() : "unknown");
     rc = (void *)tp;
   } else if ((lr.Flags.ExtendsBefore || lr.Flags.ExtendsAfter) && !IsImplicit) {
@@ -247,9 +250,9 @@
     // In addition to the mapping rules above, the close map modifier forces the
     // mapping of the variable to the device.
     if (Size) {
-      DP("Return HstPtrBegin " DPxMOD " Size=%" PRId64 " RefCount=%s\n",
-         DPxPTR((uintptr_t)HstPtrBegin), Size,
-         (UpdateRefCount ? " updated" : ""));
+      DP("Return HstPtrBegin " DPxMOD " Size=%" PRId64 " for unified shared "
+         "memory\n",
+         DPxPTR((uintptr_t)HstPtrBegin), Size);
       IsHostPtr = true;
       rc = HstPtrBegin;
     }
@@ -264,14 +267,16 @@
     // If it is not contained and Size > 0, we should create a new entry for it.
     IsNew = true;
     uintptr_t tp = (uintptr_t)allocData(Size, HstPtrBegin);
+    HostDataToTargetTy newEntry((uintptr_t)HstPtrBase, (uintptr_t)HstPtrBegin,
+                                (uintptr_t)HstPtrBegin + Size, tp, HstPtrName);
     INFO(OMP_INFOTYPE_MAPPING_CHANGED, DeviceID,
          "Creating new map entry with "
-         "HstPtrBegin=" DPxMOD ", TgtPtrBegin=" DPxMOD ", Size=%ld, Name=%s\n",
+         "HstPtrBegin=" DPxMOD ", TgtPtrBegin=" DPxMOD ", Size=%ld, "
+         "RefCount=%s, Name=%s\n",
          DPxPTR(HstPtrBegin), DPxPTR(tp), Size,
+         newEntry.refCountToStr().c_str(),
          (HstPtrName) ? getNameFromMapping(HstPtrName).c_str() : "unknown");
-    HostDataToTargetMap.emplace(
-        HostDataToTargetTy((uintptr_t)HstPtrBase, (uintptr_t)HstPtrBegin,
-                           (uintptr_t)HstPtrBegin + Size, tp, HstPtrName));
+    HostDataToTargetMap.insert(newEntry);
     rc = (void *)tp;
   }
 
@@ -294,25 +299,35 @@
   if (lr.Flags.IsContained ||
       (!MustContain && (lr.Flags.ExtendsBefore || lr.Flags.ExtendsAfter))) {
     auto &HT = *lr.Entry;
+    // We do not decrement the reference count to zero here.  deallocTgtPtr does
+    // that atomically with removing the mapping.  Otherwise, before this thread
+    // removed the mapping in deallocTgtPtr, another thread could retrieve the
+    // mapping, increment and decrement back to zero, and then both threads
+    // would try to remove the mapping, resulting in a double free.
     IsLast = HT.getRefCount() == 1;
-
-    if (!IsLast && UpdateRefCount)
+    const char *RefCountAction;
+    if (!UpdateRefCount)
+      RefCountAction = "update suppressed";
+    else if (IsLast)
+      RefCountAction = "deferred final decrement";
+    else {
+      RefCountAction = "decremented";
       HT.decRefCount();
-
+    }
     uintptr_t tp = HT.TgtPtrBegin + ((uintptr_t)HstPtrBegin - HT.HstPtrBegin);
-    DP("Mapping exists with HstPtrBegin=" DPxMOD ", TgtPtrBegin=" DPxMOD ", "
-       "Size=%" PRId64 ",%s RefCount=%s\n",
-       DPxPTR(HstPtrBegin), DPxPTR(tp), Size,
-       (UpdateRefCount ? " updated" : ""),
-       HT.isRefCountInf() ? "INF" : std::to_string(HT.getRefCount()).c_str());
+    INFO(OMP_INFOTYPE_MAPPING_EXISTS, DeviceID,
+         "Mapping exists with HstPtrBegin=" DPxMOD ", TgtPtrBegin=" DPxMOD ", "
+         "Size=%" PRId64 ", RefCount=%s (%s)\n",
+         DPxPTR(HstPtrBegin), DPxPTR(tp), Size, HT.refCountToStr().c_str(),
+         RefCountAction);
     rc = (void *)tp;
   } else if (PM->RTLs.RequiresFlags & OMP_REQ_UNIFIED_SHARED_MEMORY) {
     // If the value isn't found in the mapping and unified shared memory
     // is on then it means we have stumbled upon a value which we need to
     // use directly from the host.
-    DP("Get HstPtrBegin " DPxMOD " Size=%" PRId64 " RefCount=%s\n",
-       DPxPTR((uintptr_t)HstPtrBegin), Size,
-       (UpdateRefCount ? " updated" : ""));
+    DP("Get HstPtrBegin " DPxMOD " Size=%" PRId64 " for unified shared "
+       "memory\n",
+       DPxPTR((uintptr_t)HstPtrBegin), Size);
     IsHostPtr = true;
     rc = HstPtrBegin;
   }
Index: openmp/libomptarget/test/offloading/info.c
===================================================================
--- openmp/libomptarget/test/offloading/info.c
+++ openmp/libomptarget/test/offloading/info.c
@@ -19,10 +19,10 @@
 // INFO: Libomptarget device 0 info: alloc(A[0:64])[256]
 // INFO: Libomptarget device 0 info: tofrom(B[0:64])[256]
 // INFO: Libomptarget device 0 info: to(C[0:64])[256]
-// INFO: Libomptarget device 0 info: Creating new map entry with HstPtrBegin={{.*}}, TgtPtrBegin={{.*}}, Size=256, Name=A[0:64]
-// INFO: Libomptarget device 0 info: Creating new map entry with HstPtrBegin={{.*}}, TgtPtrBegin={{.*}}, Size=256, Name=B[0:64]
+// INFO: Libomptarget device 0 info: Creating new map entry with HstPtrBegin={{.*}}, TgtPtrBegin={{.*}}, Size=256, RefCount=1, Name=A[0:64]
+// INFO: Libomptarget device 0 info: Creating new map entry with HstPtrBegin={{.*}}, TgtPtrBegin={{.*}}, Size=256, RefCount=1, Name=B[0:64]
 // INFO: Libomptarget device 0 info: Copying data from host to device, HstPtr={{.*}}, TgtPtr={{.*}}, Size=256, Name=B[0:64]
-// INFO: Libomptarget device 0 info: Creating new map entry with HstPtrBegin={{.*}}, TgtPtrBegin={{.*}}, Size=256, Name=C[0:64]
+// INFO: Libomptarget device 0 info: Creating new map entry with HstPtrBegin={{.*}}, TgtPtrBegin={{.*}}, Size=256, RefCount=1, Name=C[0:64]
 // INFO: Libomptarget device 0 info: Copying data from host to device, HstPtr={{.*}}, TgtPtr={{.*}}, Size=256, Name=C[0:64]
 // INFO: Libomptarget device 0 info: OpenMP Host-Device pointer mappings after block at info.c:{{[0-9]+}}:{{[0-9]+}}:
 // INFO: Libomptarget device 0 info: Host Ptr           Target Ptr         Size (B) RefCount Declaration