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  1. JDK
  2. JDK-8224875

Shenandoah: ParallelCleaning code unloading should take lock to protect shared code roots array

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    • Subcomponent:
      gc
    • Resolved In Build:
      b23

      Backports

        Description

        This was found in Shenandoah testing after JDK-8224115 that exposed it to the mercy of CodeCache lock. There is apparently a path via ParallelCleaningTask that calls into nmethod::make_unloaded without the lock, which in turn calls CollectedHeap::unregister_nmethod. This definitely happens with Shenandoah, and might also happen with G1? I cannot see where CodeCache lock is taken on CH::unregister_nmethod path in G1.

        # A fatal error has been detected by the Java Runtime Environment:
        #
        # Internal Error (/home/jenkins/workspace/nightly/jdk-jdk/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp:159), pid=82156, tid=82172
        # assert(CodeCache_lock->owned_by_self()) failed: Must own CodeCache_lock
        ...

        --------------- T H R E A D ---------------

        Current thread (0x00007fd43c007000): GCTaskThread "Shenandoah GC Threads#4" [stack: 0x00007fd4440da000,0x00007fd4441da000] [id=82172]

        Stack: [0x00007fd4440da000,0x00007fd4441da000], sp=0x00007fd4441d8b30, free space=1018k
        Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
        V [libjvm.so+0x15c0d74] ShenandoahCodeRoots::remove_nmethod(nmethod*)+0x474
        V [libjvm.so+0x136d5d0] nmethod::make_unloaded()+0x3a0
        V [libjvm.so+0x1441419] ParallelCleaningTask::work(unsigned int)+0xc9
        V [libjvm.so+0x18fc7e6] GangWorker::run_task(WorkData)+0x66
        V [libjvm.so+0x18fc8d8] GangWorker::loop()+0x48
        V [libjvm.so+0x17d756b] Thread::call_run()+0xfb
        V [libjvm.so+0x13fdac9] thread_native_entry(Thread*)+0x119

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                Assignee:
                zgu Zhengyu Gu
                Reporter:
                shade Aleksey Shipilev
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                  Created:
                  Updated:
                  Resolved: