diff -r 4cbfa5077d68 -r 623722a6aeb9 src/hotspot/share/gc/shared/ptrQueue.cpp
--- a/src/hotspot/share/gc/shared/ptrQueue.cpp	Mon Nov 25 12:32:40 2019 +0100
+++ b/src/hotspot/share/gc/shared/ptrQueue.cpp	Mon Nov 25 12:33:15 2019 +0100
@@ -197,7 +197,7 @@
 bool BufferNode::Allocator::try_transfer_pending() {
   // Attempt to claim the lock.
   if (Atomic::load(&_transfer_lock) || // Skip CAS if likely to fail.
-      Atomic::cmpxchg(true, &_transfer_lock, false)) {
+      Atomic::cmpxchg(&_transfer_lock, false, true)) {
     return false;
   }
   // Have the lock; perform the transfer.