diff -r ff3eab78554f -r 765ecbffe88a src/hotspot/share/gc/shenandoah/shenandoahHeuristics.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahHeuristics.cpp	Mon Oct 21 15:11:42 2019 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoahHeuristics.cpp	Mon Oct 21 15:11:43 2019 +0200
@@ -120,6 +120,9 @@
 
   ShenandoahHeap* heap = ShenandoahHeap::heap();
 
+  // Check all pinned regions have updated status before choosing the collection set.
+  heap->assert_pinned_region_status();
+
   // Step 1. Build up the region candidates we care about, rejecting losers and accepting winners right away.
 
   size_t num_regions = heap->num_regions();