JVM crashes in print_locked_object_class_name

Issue

• Our JVM crashed in the VM Thread when trying to generate thread dumps in response to jstack:

Stack: [0x00002ae5e8562000,0x00002ae5e8663000],  sp=0x00002ae5e86618c0,  free space=1022k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0x64187b]  Klass::external_name() const+0x1b
V  [libjvm.so+0x8970f6]  print_locked_object_class_name(outputStream*, Handle, char const*)+0xb6
V  [libjvm.so+0x897da9]  javaVFrame::print_lock_info_on(outputStream*, int)+0x149
V  [libjvm.so+0x862591]  JavaThread::print_stack_on(outputStream*)+0x1e1
V  [libjvm.so+0x862b1b]  Threads::print_on(outputStream*, bool, bool, bool)+0x4db
V  [libjvm.so+0x8aac8c]  VM_Operation::evaluate()+0x4c
V  [libjvm.so+0x8a96a0]  VMThread::evaluate_operation(VM_Operation*)+0x80
V  [libjvm.so+0x8a9c26]  VMThread::loop()+0x1e6
V  [libjvm.so+0x8aa2c0]  VMThread::run()+0x70
V  [libjvm.so+0x744270]  java_start(Thread*)+0x100