IJ48866: JAVA JIT: CRASH DUE TO STALE DATA RUNNING ON POWER OR AARCH64 CPUS

APAR status

• Closed as program error.

Error description

• Error Message: SIGSEGV (signal 11/0xB) when running inside JIT
  compiled code.
  .
  Stack Trace: N/A
  .
  The problem can result in a number of different symptoms
  including a crash inside JIT compiled code, a crash in the
  interpreter (J9VM), an unexpected exception or a crash in the
  garbage collector.
  The problem can only occur on JVMs running on the POWER or
  AArch64 architectures. For POWER, that includes AIX, LinuxPPC
  and LinuxPPCle.
  The problem will only occur intermittently because it is very
  timing dependant.
  

Local fix

• The problem can be avoiding by exporting the following
  environment variable in the shell that is running java:
  TR_disableFastArrayClone=1
  This option disables only a very small part of the JIT compiler
  and therefore will have a very small performance impact.
  

Problem summary

• On the POWER architecture we need to issue a special instruction
  
  to guarantee the visibility of the memory contents for new
  objects by threads other then the one the allocated the object.
  There exist two locations in the JIT compiler where this
  instruction was not being issues which would allow threads to
  see stale memory contents which could result in many different
  failure symptoms.
  The two cases are:
  1. Inlining Object.clone() for arrays objects
  2. Inlining StringUFT16.toBytes() **Java 11+ only**
  

Problem conclusion

• The JIT was modified to ensure the proper memory flush
  instruction is executed when inlining calls to Object.clone()
  and StringUFT16.toBytes()
  https://github.com/eclipse/omr/pull/7117
  https://github.com/eclipse-openj9/openj9/pull/18154
  .
  This APAR will be fixed in the following Releases:
  .
  IBM Semeru Runtimes
    17              17.0.10.0
    11              11.0.22.0
  IBM SDK, Java Technology Edition
    8    SR8 FP20  (8.0.8.20)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  maintenance can be found at:
            https://www.ibm.com/support/pages/java-sdk
  

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