IJ05155: JAVA JIT: CRASH INSIDE A JIT COMPILED SYNRONIZED BLOCK

APAR status

• Closed as program error.

Error description

• Error Message: A SIG_SEGV is received inside a compiled method
  when running Java 7.1 or Java 8.0 on a Power8 CPU.
  .
  Stack Trace: N/A
  .
  The problem can only occur when using transaction memory
  instructions on Power8. Only Java 7.1 and Java 8.0 make use of
  these instructions.
  The problem only happens on synchronized blocks where the
  variable being locked is a NULL reference. Typically attempting
  to synchronize against a null reference would be considered a
  programming error in the source java code.
  

Local fix

• The issue can be avoided with a negligible impact on performance
  by using the following Java command line option:
  -Xjit:disableTLE
  

Problem summary

• The JIT would fail to generate a null-check on the variable used
  as the object in a synchronized block that is being converted
  into a transactional memory lock region. This would allow for
  the possibility of a store attempt to a NULL pointer which
  results in a SIG_SEGV.
  

Problem conclusion

• The JIT was modified so that a Null-check would be generated
  before entering the transactional memory lock region. With this
  fix in place the java code will correctly throw a
  NullPointerException rather then crash.
  .
  This APAR will be fixed in the following Java Releases:
     7 R1 SR4 FP25  (7.1.4.25)
     8    SR5 FP15  (8.0.5.15)
  .
  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