--- old/src/share/vm/runtime/os.cpp	2014-12-17 15:24:48.164461287 +0100
+++ new/src/share/vm/runtime/os.cpp	2014-12-17 15:24:48.095459301 +0100
@@ -1590,7 +1590,7 @@
 
 void os::pretouch_memory(char* start, char* end) {
   for (volatile char *p = start; p < end; p += os::vm_page_size()) {
-    char t = *p; *p = t;
+    *p = 0;
   }
 }
 
--- old/src/share/vm/runtime/os.hpp	2014-12-17 15:24:48.551472427 +0100
+++ new/src/share/vm/runtime/os.hpp	2014-12-17 15:24:48.482470441 +0100
@@ -311,6 +311,10 @@
   static bool   uncommit_memory(char* addr, size_t bytes);
   static bool   release_memory(char* addr, size_t bytes);
 
+  // Touch memory pages that cover the memory range from start to end (exclusive)
+  // to make the OS back the memory range with actual memory.
+  // Current implementation may not touch the last page if unaligned addresses
+  // are passed.
   static void   pretouch_memory(char* start, char* end);
 
   enum ProtType { MEM_PROT_NONE, MEM_PROT_READ, MEM_PROT_RW, MEM_PROT_RWX };