Index: gc.c
===================================================================
--- gc.c	(revision 60140)
+++ gc.c	(working copy)
@@ -6874,6 +6874,10 @@
  *     GC.latest_gc_info(:major_by) -> :malloc
  *
  *  Returns information about the most recent garbage collection.
+ *
+ *  If the optional argument, hash, is given,
+ *  it is overwritten and returned.
+ *  This is intended to avoid probe effect.
  */
 
 static VALUE
@@ -7245,6 +7249,10 @@
  *          :oldmalloc_increase_bytes_limit=>16777216
  *      }
  *
+ *  If the optional argument, hash, is given,
+ *  it is overwritten and returned.
+ *  This is intended to avoid probe effect.
+ *
  *  The contents of the hash are implementation specific and may be changed in
  *  the future.
  *