IV99779: GC ASSERTION WHEN WALKING A JIT COMPILED FRAME

APAR status

• Closed as program error.

Error description

• Error Message: Object neither in heap nor stack-allocated
  ...
  ** ASSERTION FAILED ** at
  ../../../../gc_glue_java/ScavengerRootScanner.hpp
  ((MM_StackSlotValidator(MM_StackSlotValidator::NOT_ON_HEAP,
  *slotPtr, stackLocation, walkState).validate(_env)))
  .
  Stack Trace: MM_ScavengerRootScanner::doStackSlot(J9Object**,
  void*, void const*) ()
  stackSlotIterator(J9JavaVM*, J9Object**, void*,
  J9StackWalkState*, void const*) ()
  vmThreadStackDoOSlotIterator(J9VMThread*, J9StackWalkState*,
  J9Object**, void const*) ()
  walkJITFrameSlotsForInternalPointers$AF137_66 ()
  IPRA.$walkJITFrameSlots ()
  IPRA.$jitWalkFrame ()
  jitWalkStackFrames ()
  walkStackFrames ()
  GC_VMThreadStackSlotIterator::scanSlots(J9VMThread*,
  J9VMThread*, void*, void (*)(J9JavaVM*, J9Object**, void*,
  J9StackWalkState*, void const*), bool, bool) ()
  MM_RootScanner::scanOneThread(MM_EnvironmentBase*, J9VMThread*,
  void*) ()
  MM_RootScanner::scanThreads(MM_EnvironmentBase*) ()
  MM_RootScanner::scanRoots(MM_EnvironmentBase*) ()
  .
  

Local fix

• The problem can be avoided by using the option
  -Xjit:disableInternalPointers
  Note however this may have a minor performance impact.
  

Problem summary

• This problem is caused by incorrectly marking native pointers as
  garbage collectable references. A GC assertion would occur when
  the GC tries to validate the native pointer as a java object.
  

Problem conclusion

• The JIT compiler has been updated to stop marking native
  pointers as collectable references.
  .
  This APAR will be fixed in the following Java Releases:
   8 SR5 (8.0.5.0)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  Service Refreshes and Fix Packs can be found at:
   https://www.ibm.com/developerworks/java/jdk/
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels

• R130 PSY

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