guarantee(object->mark() == markWord::INFLATING()) failed: invariant

[Doerr, Martin]

Hi,

we have seen a crash when running Spec JVM 2008 on a Power9 machine.
It occurred only once so I can't tell if it is a PPC64 specific or weak memory model specific issue.
Locking code has worked very solid for many years on this platform.

#  Internal Error (synchronizer.cpp:1953), pid=18455, tid=19363
#  guarantee(object->mark() == markWord::INFLATING()) failed: invariant

V  [libjvm.so+0xe463cc]  ObjectSynchronizer::inflate(Thread*, oopDesc*, ObjectSynchronizer::InflateCause)+0x76c
V  [libjvm.so+0xe467ac]  ObjectSynchronizer::exit(oopDesc*, BasicLock*, Thread*)+0x4c
V  [libjvm.so+0xda18a0]  SharedRuntime::complete_monitor_unlocking_C(oopDesc*, BasicLock*, JavaThread*)+0xc0
J 5765 c2 sun.nio.cs.StreamEncoder.flushBuffer()V java.base at 16.0.0.1-internal (42 bytes) @ 0x00007fff95e1d84c [0x00007fff95e1d400+0x000000000000044c]
J 6249 c2 java.io.PrintStream.println(Ljava/lang/String;)V java.base at 16.0.0.1-internal (44 bytes) @ 0x00007fff95f1f1a0 [0x00007fff95f1ea80+0x0000000000000720]
J 6534 c1 spec.benchmarks.crypto.aes.Main.runEncryptDecrypt(Ljavax/crypto/SecretKey;Ljava/lang/String;Ljava/lang/String;)V (93 bytes) @ 0x00007fff8e575794 [0x00007fff8e574e00+0x0000000000000994]
j  spec.benchmarks.crypto.aes.Main.harnessMain()V+69
...

object->_mark points to a stack lock:
0x00007ffe67dfdbc8 is pointing into the stack for thread: 0x00007ffeec10d5e0
content of stack slot 0x7ffe67dfdbc8: 0x0000000000000009
which belongs to the crashing thread:
Current thread (0x00007ffeec10d5e0):  JavaThread "BenchmarkThread crypto.aes 5" [_thread_in_Java, id=19363, stack(0x00007ffe67c00000,0x00007ffe67e00000)]

I wonder how this can happen. Can it be related to asynchronous lock deflation?
Any ideas are welcome.

Best regards,
Martin