diff -r ff3eab78554f -r 765ecbffe88a src/hotspot/share/gc/shenandoah/shenandoahMarkCompact.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahMarkCompact.cpp	Mon Oct 21 15:11:42 2019 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoahMarkCompact.cpp	Mon Oct 21 15:11:43 2019 +0200
@@ -128,6 +128,9 @@
     // e. Set back forwarded objects bit back, in case some steps above dropped it.
     heap->set_has_forwarded_objects(has_forwarded_objects);
 
+    // f. Sync pinned region status from the CP marks
+    heap->sync_pinned_region_status();
+
     // The rest of prologue:
     BiasedLocking::preserve_marks();
     _preserved_marks->init(heap->workers()->active_workers());
@@ -505,6 +508,10 @@
 
   ShenandoahHeap* heap = ShenandoahHeap::heap();
 
+  // About to figure out which regions can be compacted, make sure pinning status
+  // had been updated in GC prologue.
+  heap->assert_pinned_region_status();
+
   {
     // Trash the immediately collectible regions before computing addresses
     ShenandoahTrashImmediateGarbageClosure tigcl;