mmap(2) says that you must call mmap() with either MAP_SHARED or

MAP_PRIVATE.  We didn't catch this because we checked for a NULL
return, not a -1 return.  Doh!  Thanks again to Julian Seward for
continuing to track this down.

This commit was SVN r22062.

opal/mca/memory/ptmalloc2/opal_ptmalloc2_component.c

@@ -133,8 +133,8 @@ static int ptmalloc2_open(void)
         val |= OPAL_MEMORY_FREE_SUPPORT | OPAL_MEMORY_CHUNK_SUPPORT;
     }
 
-    p = mmap(NULL, 4096, PROT_READ, MAP_ANONYMOUS, -1, 0);
-    if (NULL == p) {
+    p = mmap(NULL, 4096, PROT_READ, (MAP_ANONYMOUS | MAP_PRIVATE), -1, 0);
+    if (((void*) -1) == p) {
         return OPAL_ERR_OUT_OF_RESOURCE;
     }
     munmap(p, 4096);