runtime: fix struct comment

Change-Id: I0c33830b13c8a187ac82504c7653abb8f8cf7530
Reviewed-on: https://go-review.googlesource.com/c/go/+/681655
Reviewed-by: Sean Liao <sean@liao.dev>
Reviewed-by: Junyang Shao <shaojunyang@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Sean Liao <sean@liao.dev>

diff --git a/src/runtime/mheap.go b/src/runtime/mheap.go
index 3965d6eb52de4e95e407bbe77b2de7bc0bf17911..f25dbb429d7f78b66582fdea3bfe0428a53fd36d 100644 (file)
--- a/src/runtime/mheap.go
+++ b/src/runtime/mheap.go
@@ -312,8 +312,10 @@ type heapArena struct {
        // during marking.
        pageSpecials [pagesPerArena / 8]uint8
 
-       // pageUseSpanDartboard is a bitmap that indicates which spans are
-       // heap spans and also gcUsesSpanDartboard.
+       // pageUseSpanInlineMarkBits is a bitmap where each bit corresponds
+       // to a span, as only spans one page in size can have inline mark bits.
+       // The bit indicates that the span has a spanInlineMarkBits struct
+       // stored directly at the top end of the span's memory.
        pageUseSpanInlineMarkBits [pagesPerArena / 8]uint8
 
        // checkmarks stores the debug.gccheckmark state. It is only