8371369: Parallel: Relax precondition of PSOldGen::expand_and_allocate

Reviewed-by: eosterlund, fandreuzzi

Author: albertnetymk

src/hotspot/share/gc/parallel/mutableSpace.cpp

@@ -182,12 +182,11 @@ bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) {
 
 // Only used by oldgen allocation.
 bool MutableSpace::needs_expand(size_t word_size) const {
-#ifdef ASSERT
-  // If called by VM thread, locking is not needed.
-  if (!Thread::current()->is_VM_thread()) {
-    assert_lock_strong(PSOldGenExpand_lock);
-  }
-#endif
+  // This method can be invoked either outside of safepoint by java threads or
+  // in safepoint by gc workers. Such accesses are synchronized by holding one
+  // of the following locks.
+  assert(Heap_lock->is_locked() || PSOldGenExpand_lock->is_locked(), "precondition");
+
   // Holding the lock means end is stable.  So while top may be advancing
   // via concurrent allocations, there is no need to order the reads of top
   // and end here, unlike in cas_allocate.

src/hotspot/share/gc/parallel/psOldGen.cpp

@@ -118,8 +118,8 @@ void PSOldGen::initialize_performance_counters() {
 }
 
 HeapWord* PSOldGen::expand_and_allocate(size_t word_size) {
-  assert(SafepointSynchronize::is_at_safepoint(), "precondition");
-  assert(Thread::current()->is_VM_thread(), "precondition");
+  assert(Heap_lock->is_locked(), "precondition");
+
   if (object_space()->needs_expand(word_size)) {
     expand(word_size*HeapWordSize);
   }