diff -r a9933c6c5a95 -r cc62dbe71e6a hotspot/src/share/vm/memory/allocation.inline.hpp
--- a/hotspot/src/share/vm/memory/allocation.inline.hpp	Thu Feb 10 14:25:59 2011 -0800
+++ b/hotspot/src/share/vm/memory/allocation.inline.hpp	Thu Feb 10 19:34:48 2011 -0800
@@ -32,12 +32,20 @@
 void trace_heap_malloc(size_t size, const char* name, void *p);
 void trace_heap_free(void *p);
 
+#ifndef PRODUCT
 // Increments unsigned long value for statistics (not atomic on MP).
 inline void inc_stat_counter(volatile julong* dest, julong add_value) {
+#if defined(SPARC) || defined(X86)
+  // Sparc and X86 have atomic jlong (8 bytes) instructions
   julong value = Atomic::load((volatile jlong*)dest);
   value += add_value;
   Atomic::store((jlong)value, (volatile jlong*)dest);
+#else
+  // possible word-tearing during load/store
+  *dest += add_value;
+#endif
 }
+#endif
 
 // allocate using malloc; will fail if no memory available
 inline char* AllocateHeap(size_t size, const char* name = NULL) {