IV82442: CRASH IN JITINSTANCEOF DURING THE DEREFERENCE OF AN UNLOADED CLA SS

APAR status

• Closed as program error.

Error description

• Error Message: A segmentation error is thrown when the compiled
  code tries to dereference a class reference whose value is
  invalid because the class it refers to has been unloaded.
  .
  Stack Trace: Unhandled exception
  Type=Segmentation error vmState=0x00040000
  J9Generic_Signal_Number=00000004 ExceptionCode=c0000005
  ExceptionAddress=6EEFAEC2 ContextFlags=0001003f
  Handler1=6F3CF230 Handler2=6F388520
  InaccessibleReadAddress=00000010
  EDI=236DD900 ESI=00000000 EAX=251ABF00 EBX=236DD900
  ECX=00000000 EDX=236DD900
  EIP=6EEFAEC2 ESP=23FCC6D0 EBP=23079400 EFLAGS=00010206
  GS=002B FS=0053 ES=002B DS=002B
  Module=j9jit28.dll
  Module_base_address=6E970000 Offset_in_DLL=0058aec2
  Target=2_90_20160206_289328 (Windows 8.1 6.3 build 9600)
  CPU=x86 (2 logical CPUs) (0xfff8d000 RAM)
  ----------- Stack Backtrace -----------
  jitInstanceOf+0x82 (nathelp.asm:4228, 0x6EEFAEC2
  <OSB>j9jit28+0x58aec2<CSB>)
  (0x237D3DDF)
  (0x251ABF00)
  (0x224D8D68)
  (0x2307EC78)
  .
  

Local fix

• This issue can be worked around using the
  -Xjit:disableLoopVersioner option globally or on the affected
  methods. Note however that this workaround is likely to have a
  noticeable negative performance impact, especially when used
  globally.
  

Problem summary

• In some circumstances the JIT may generate an instanceof test as
  part of rearranging program code to improve performance. Under
  some rare circumstances this instanceof test can fail
  unexpectedly due to class unloading - the JIT moves the
  instanceof beyond the guards protecting it from this event. This
  invalid state can result in a program crash or in very rare
  circumstances an incorrect result being computed.
  

Problem conclusion

• The JIT compiler has been updated to ensure that the motion of
  instanceofs correctly accounts for potential class unloading
  during compiled method execution.
  .
  This APAR will be fixed in the following Java Releases:
     8    SR3       (8.0.3.0)
     7    SR9 FP40  (7.0.9.40)
     6 R1 SR8 FP25  (6.1.8.25)
     6    SR16 FP25 (6.0.16.25)
  .
  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:

Fix information

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels

• R130 PSY

     UP

• R260 PSY

     UP

• R600 PSY

     UP