diff --git a/ompi/class/ompi_pointer_array.h b/ompi/class/ompi_pointer_array.h
index cd423a3a34..2fc21a3236 100644
--- a/ompi/class/ompi_pointer_array.h
+++ b/ompi/class/ompi_pointer_array.h
@@ -145,6 +145,25 @@ static inline int ompi_pointer_array_get_size(ompi_pointer_array_t *array)
 OMPI_DECLSPEC bool ompi_pointer_array_test_and_set_item (ompi_pointer_array_t *table, 
                                           int index,
                                           void *value);
+
+/**
+ * Empty the array.
+ *
+ * @param array Pointer to array (IN)
+ *
+ */
+static inline void ompi_pointer_array_remove_all(ompi_pointer_array_t *array)
+{
+  int i;
+  OPAL_THREAD_LOCK(&array->lock);
+  array->lowest_free = 0;
+  array->number_free = array->size;
+  for(i=0; i<array->size; i++) {
+      array->addr[i] = NULL;
+  }
+  OPAL_THREAD_UNLOCK(&array->lock);
+}
+
 #if defined(c_plusplus) || defined(__cplusplus)
 }
 #endif
diff --git a/ompi/mca/mpool/base/mpool_base_alloc.c b/ompi/mca/mpool/base/mpool_base_alloc.c
index a01067c840..1ed7543454 100644
--- a/ompi/mca/mpool/base/mpool_base_alloc.c
+++ b/ompi/mca/mpool/base/mpool_base_alloc.c
@@ -242,7 +242,7 @@ int mca_mpool_base_free(void * base)
                 &cnt
                 );
             if(OMPI_SUCCESS != rc) {
-                goto cleanup;
+                continue;
             }
             for(i = 0; i < cnt; i++) {
                 mca_mpool_base_registration_t* reg = (mca_mpool_base_registration_t*)
@@ -253,6 +253,7 @@ int mca_mpool_base_free(void * base)
                     goto cleanup;
                 }
             }
+            ompi_pointer_array_remove_all(&regs);
         }
     }
 
diff --git a/ompi/mca/mpool/base/mpool_base_mem_cb.c b/ompi/mca/mpool/base/mpool_base_mem_cb.c
index b3737d757c..6ddc5c10eb 100644
--- a/ompi/mca/mpool/base/mpool_base_mem_cb.c
+++ b/ompi/mca/mpool/base/mpool_base_mem_cb.c
@@ -18,6 +18,8 @@
  */
 #include "mpool_base_mem_cb.h"
 #include "base.h"
+#include "orte/util/proc_info.h"
+#include "mca/ns/ns_types.h"
 
 
 extern uint32_t mca_mpool_base_page_size; 
@@ -33,6 +35,7 @@ void mca_mpool_base_mem_cb(void* base, size_t size, void* cbdata)
     mca_mpool_base_registration_t* reg;
     mca_mpool_base_selected_module_t* current;
     int rc;
+    int dereg = 0;
     opal_list_item_t* item;
     void* base_addr; 
     void* bound_addr; 
@@ -66,8 +69,8 @@ void mca_mpool_base_mem_cb(void* base, size_t size, void* cbdata)
                 for(i = 0; i < cnt; i++) { 
                 
                     reg = (mca_mpool_base_registration_t*)ompi_pointer_array_get_item(&regs, i);
-                    if(base_addr <  (void*) ((unsigned long) reg->bound - mca_mpool_base_page_size + 1)) { 
-                        base_addr = (reg->bound - mca_mpool_base_page_size + 1); 
+                    if(base_addr <  (void*) ((unsigned long) reg->bound - mca_mpool_base_page_size)) { 
+                        base_addr = reg->bound - mca_mpool_base_page_size; 
                     }
                     if(reg->flags & MCA_MPOOL_FLAGS_CACHE) { 
                         assert(reg->ref_count <= 3);
@@ -76,13 +79,26 @@ void mca_mpool_base_mem_cb(void* base, size_t size, void* cbdata)
                     } else { 
                         assert(reg->ref_count <= 1); 
                     }
+#if 0
+                    fprintf(stderr, "[%lu,%lu,%lu] mca_mpool_base_mem_cb: base %p bound %p len %lu refcnt %d\n",
+                        ORTE_NAME_ARGS(orte_process_info.my_name), reg->base, reg->bound, 
+                        reg->bound-reg->base+1, reg->ref_count);
+#endif
                     current->mpool_module->mpool_deregister(current->mpool_module, reg); 
+                    dereg++;
                 }
+                ompi_pointer_array_remove_all(&regs);
             }
         }
-        
     }    
     OBJ_DESTRUCT(&regs);
+#if 0
+    if(dereg != 0) {
+        fprintf(stderr, "[%lu,%lu,%lu] mca_mpool_base_mem_cb: addr %p size %lu base %p bound %p\n", 
+            ORTE_NAME_ARGS(orte_process_info.my_name), base, size,
+            down_align_addr( base, mca_mpool_base_page_size_log), bound_addr);
+    }
+#endif
 }
 
 
diff --git a/ompi/mca/mpool/base/mpool_base_open.c b/ompi/mca/mpool/base/mpool_base_open.c
index c4dc391b54..d645467da1 100644
--- a/ompi/mca/mpool/base/mpool_base_open.c
+++ b/ompi/mca/mpool/base/mpool_base_open.c
@@ -93,7 +93,6 @@ int mca_mpool_base_open(void)
     /* get the page size for this architecture*/ 
     mca_mpool_base_page_size = sysconf(_SC_PAGESIZE); 
     mca_mpool_base_page_size_log = my_log2(mca_mpool_base_page_size); 
-    
     return OMPI_SUCCESS;
 }
 
diff --git a/ompi/mca/pml/ob1/pml_ob1_rdma.c b/ompi/mca/pml/ob1/pml_ob1_rdma.c
index 4507150bfc..f05710c522 100644
--- a/ompi/mca/pml/ob1/pml_ob1_rdma.c
+++ b/ompi/mca/pml/ob1/pml_ob1_rdma.c
@@ -20,9 +20,11 @@
 #include "ompi_config.h"
 #include <sched.h>
 #include "ompi/include/constants.h"
+#include "orte/util/proc_info.h"
 #include "mca/pml/pml.h"
 #include "mca/btl/btl.h"
 #include "mca/bml/bml.h"
+#include "mca/ns/ns_types.h"
 #include "mca/mpool/mpool.h" 
 #include "pml_ob1.h"
 #include "pml_ob1_rdma.h"
@@ -39,8 +41,8 @@ size_t mca_pml_ob1_rdma_btls(
     mca_pml_ob1_rdma_btl_t* rdma_btls)
 {
     size_t num_btls = mca_bml_base_btl_array_get_size(&bml_endpoint->btl_rdma);
-    size_t num_btls_used = 0;
     ompi_pointer_array_t regs;
+    size_t num_btls_used = 0;
     size_t n;
     
     /* shortcut when there are no rdma capable btls */
@@ -68,6 +70,7 @@ size_t mca_pml_ob1_rdma_btls(
         }
  
         /* look through existing registrations */
+        ompi_pointer_array_remove_all(&regs);
         btl_mpool->mpool_find(btl_mpool, 
                               base,
                               size,
@@ -91,14 +94,7 @@ size_t mca_pml_ob1_rdma_btls(
 
             /* otherwise if leave_pinned re-register */
             } else if( mca_pml_ob1.leave_pinned ) {
-                mca_mpool_base_registration_t reg_temp;
-                unsigned char* new_base = reg->base < base ? reg->base : base;
-                unsigned char* new_bound = reg->bound > (base + size - 1) ? reg->bound : (base + size - 1);  
-                size_t new_len = new_bound - new_base + 1;
-                
-                /* printf("re-reg 2: base %p size %d new_base %p new_len %d\n", base, size, new_base, new_len);  */
-                assert(new_len >= size);
-                reg_temp = *reg; 
+
                 btl_mpool->mpool_deregister(btl_mpool, reg); 
                 btl_mpool->mpool_register(btl_mpool, 
                     base, 
@@ -158,16 +154,13 @@ size_t mca_pml_ob1_rdma_btls(
 
             /* a registration exists but is not large enough */
             } else {
-                unsigned char* new_base = largest->base;
-                size_t new_len = (base - largest->base) + size;
 
                 /* simplify cleanup - bump reference count as we decrement again below */
                 btl_mpool->mpool_retain(btl_mpool,largest);
                 btl_mpool->mpool_deregister(btl_mpool, largest);
-                assert(new_len >= size);
                 btl_mpool->mpool_register(btl_mpool, 
-                    new_base, 
-                    new_len, 
+                    base, 
+                    size, 
                     MCA_MPOOL_FLAGS_CACHE,
                     &fit); 
                 assert(fit->ref_count == 3);
@@ -188,7 +181,6 @@ size_t mca_pml_ob1_rdma_btls(
             num_btls_used++;
         }
     }
-    OBJ_DESTRUCT(&regs);
     return num_btls_used;
 }
 
@@ -224,7 +216,35 @@ mca_mpool_base_registration_t* mca_pml_ob1_rdma_registration(
         size,
         &regs, 
         &reg_cnt); 
+
     assert(reg_cnt <= 1);
+    /* shortcut for one entry - the typical case */
+    if(reg_cnt == 1) {
+        mca_mpool_base_registration_t* reg  = ompi_pointer_array_get_item(&regs, 0); 
+        size_t reg_len = reg->bound - base + 1;
+
+        /* is the existing registration the required size */
+        if(reg->base <= base && reg_len >= size) {
+            return reg;
+
+        /* otherwise if leave_pinned re-register */
+        } else if ( mca_pml_ob1.leave_pinned ) {
+          
+            btl_mpool->mpool_deregister(btl_mpool, reg); 
+            btl_mpool->mpool_register(btl_mpool, 
+                base, 
+                size, 
+                MCA_MPOOL_FLAGS_CACHE,
+                &reg); 
+            return reg;
+
+        /* existing registration cannot be used */
+        } else {
+            btl_mpool->mpool_release(btl_mpool, reg);
+            return NULL;
+        }
+    }
+
     for(r = 0; r < reg_cnt; r++) { 
         mca_mpool_base_registration_t* reg  = ompi_pointer_array_get_item(&regs, r); 
         size_t reg_len = reg->bound - base + 1;
@@ -259,14 +279,9 @@ mca_mpool_base_registration_t* mca_pml_ob1_rdma_registration(
            assert(fit->ref_count >= 3);
        /* a registration exists but is not large enough */
        } else {
-           unsigned char* new_base = largest->base < base ? largest->base: base;
-           unsigned char* new_bound = largest->bound > (base + size - 1) ? largest->bound : (base + size - 1);  
-           size_t new_len = new_bound - new_base + 1;
-           
-           /* printf("re-reg 2: base %p size %d new_base %p new_len %d\n", base, size, new_base, new_len);  */
            
+           btl_mpool->mpool_retain(btl_mpool, largest);
            btl_mpool->mpool_deregister(btl_mpool, largest);
-           assert(new_len >= size);
            btl_mpool->mpool_register(btl_mpool,
                base,
                size,
diff --git a/ompi/mca/pml/ob1/pml_ob1_recvreq.c b/ompi/mca/pml/ob1/pml_ob1_recvreq.c
index 8d8190ec23..6b3e4b03e7 100644
--- a/ompi/mca/pml/ob1/pml_ob1_recvreq.c
+++ b/ompi/mca/pml/ob1/pml_ob1_recvreq.c
@@ -403,10 +403,11 @@ static void mca_pml_ob1_recv_request_rget(
         bml_btl, 
         recvreq->req_recv.req_base.req_addr,
         recvreq->req_recv.req_bytes_packed);
-    
-    recvreq->req_rdma[0].bml_btl = bml_btl; 
-    recvreq->req_rdma[0].btl_reg = reg;
-    recvreq->req_rdma_cnt = 1;
+    if(NULL != reg) {
+         recvreq->req_rdma[0].bml_btl = bml_btl; 
+         recvreq->req_rdma[0].btl_reg = reg;
+         recvreq->req_rdma_cnt = 1;
+    }
     
     /* prepare descriptor */
     mca_bml_base_prepare_dst(
diff --git a/ompi/mca/rcache/rb/rcache_rb.c b/ompi/mca/rcache/rb/rcache_rb.c
index d7a1736cad..c0351c560f 100644
--- a/ompi/mca/rcache/rb/rcache_rb.c
+++ b/ompi/mca/rcache/rb/rcache_rb.c
@@ -73,9 +73,6 @@ int mca_rcache_rb_find (
     }
     
     
-    OBJ_DESTRUCT(regs); 
-    OBJ_CONSTRUCT(regs, ompi_pointer_array_t);
-    
     pos =  ompi_pointer_array_add(regs, (void*) tree_item->reg); 
     if(0 != pos) {
         opal_output(0, "error inserting registration in 1st position");