diff --git a/src/runtime/mgcmark.go b/src/runtime/mgcmark.go
index 286aeb74a9..7819698def 100644
--- a/src/runtime/mgcmark.go
+++ b/src/runtime/mgcmark.go
@@ -973,7 +973,7 @@ func gcDrain(gcw *gcWork, flags gcDrainFlags) {
 
 	// Drain root marking jobs.
 	if work.markrootNext < work.markrootJobs {
-		for blocking || !gp.preempt {
+		for !(preemptible && gp.preempt) {
 			job := atomic.Xadd(&work.markrootNext, +1) - 1
 			if job >= work.markrootJobs {
 				break