//
// The small objects on the MCache and MCentral free lists
// may or may not be zeroed. They are zeroed if and only if
-// the second word of the object is zero. The spans in the
-// page heap are always zeroed. When a span full of objects
-// is returned to the page heap, the objects that need to be
-// are zeroed first. There are two main benefits to delaying the
+// the second word of the object is zero. A span in the
+// page heap is zeroed unless s->needzero is set. When a span
+// is allocated to break into small objects, it is zeroed if needed
+// and s->needzero is set. There are two main benefits to delaying the
// zeroing this way:
//
// 1. stack frames allocated from the small object lists
-// can avoid zeroing altogether.
+// or the page heap can avoid zeroing altogether.
// 2. the cost of zeroing when reusing a small object is
// charged to the mutator, not the garbage collector.
//