3741 zfs needs better comments
Submitted by:   Will Andrews <willa@spectralogic.com>
Submitted by:   Justin Gibbs <justing@spectralogic.com>
Submitted by:   Alan Somers <alans@spectralogic.com>
Reviewed by:    Matthew Ahrens <mahrens@delphix.com>

@@ -1822,11 +1822,11 @@
 }
 
 void
 dmu_fini(void)
 {
-        arc_fini();
+        arc_fini(); /* arc depends on l2arc, so arc must go first */
         l2arc_fini();
         zfetch_fini();
         dbuf_fini();
         dnode_fini();
         dmu_objset_fini();