re #13613 rb4516 Tunables needs volatile keyword

@@ -18,10 +18,11 @@
  *
  * CDDL HEADER END
  */
 /*
  * Copyright (c) 1990, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
  * Copyright 2015 Joyent, Inc.
  */
 
 #include <sys/types.h>
 #include <sys/param.h>

@@ -155,12 +156,12 @@
  * anon allocations will fail.
  *
  * There is also a per mount limit on the amount of swap space
  * (tmount.tm_anonmax) settable via a mount option.
  */
-size_t tmpfs_maxkmem = 0;
-size_t tmpfs_minfree = 0;
+volatile size_t tmpfs_maxkmem = 0;
+volatile size_t tmpfs_minfree = 0;
 size_t tmp_kmemspace;           /* bytes of kernel heap used by all tmpfs */
 
 static major_t tmpfs_major;
 static minor_t tmpfs_minor;
 static kmutex_t tmpfs_minor_lock;