- /* This is the offset from the start of the page to the start of
- * the alloc_region which contains/contained it.
+ /* This is the offset from the first byte of some object in memory
+ * prior to and no closer than the start of the page to the start
+ * of the page. Lower values here are better, 0 is ideal. This
+ * is useful for determining where to start when scanning forward
+ * through a heap page (either for conservative root validation or
+ * for scavenging).