IV86126: RANDOM PROCESSES CORE DUMP ON POWER8 RUNNING IBM JAVA 8 APPLIES TO AIX 7100-04

APAR status

• Closed as program error.

Error description

• **************************************************************
  * USERS AFFECTED:
    * Systems running the AIX 7100-04 Technology Level
    * with bos.pmapi.pmsvcs below the 7.1.4.30 level.
    **************************************************************
    * PROBLEM DESCRIPTION:
    * Random processes may core dump on AIX running on Power8.
    * This can happen when running applications that use the
    * event-based branching facility (EBB) and the enhanced
    * performance monitoring unit (PMU) to gather data in both
    * user space and kernel space.
    *
    * This has been seen to happen when running IBM Java 8,
    * which utilizes the EBB facility when the Runtime
    * Instrumentation (RI) facility is enabled.  RI is enabled by
    * default on IBM Java 8.
    *
    * The applications using the EBB facility function correctly,
    * but may cause other random processes to core dump
    * during context switching.
    * The core dumps will happen when branching to an invalid
    * address, and all cores would show the same invalid address.
    **************************************************************
    * RECOMMENDATION:
    * Install APAR IV86126.
    * Prior to fix availability, an interim fix is available from
    * either
    * ftp://aix.software.ibm.com/aix/ifixes/iv86126/
    * https://aix.software.ibm.com/aix/ifixes/iv86126/
    * Installation of the ifix requires a reboot.
    **************************************************************
  

Local fix

• A temporary fix could be to run in Power 7 Compatibility Mode.
  .
  For IBM Java 8 specifically, the RI facility can be disabled
  with the JVM command line option:
  -XX: -RuntimeInstrumentation
  

Problem summary

•   **************************************************************
    * USERS AFFECTED:
    * Systems running the AIX 7100-04 Technology Level
    * with bos.pmapi.pmsvcs below the 7.1.4.30 level.
    **************************************************************
    * PROBLEM DESCRIPTION:
    * Random processes may core dump on AIX running on Power8.
    * This can happen when running applications that use the
    * event-based branching facility (EBB) and the enhanced
    * performance monitoring unit (PMU) to gather data in both
    * user space and kernel space.
    *
    * This has been seen to happen when running IBM Java 8,
    * which utilizes the EBB facility when the Runtime
    * Instrumentation (RI) facility is enabled.  RI is enabled by
    * default on IBM Java 8.
    *
    * The applications using the EBB facility function correctly,
    * but may cause other random processes to core dump
    * during context switching.
    * The core dumps will happen when branching to an invalid
    * address, and all cores would show the same invalid address.
    **************************************************************
    * RECOMMENDATION:
    * Install APAR IV86126.
    * Prior to fix availability, an interim fix is available from
    * either
    * ftp://aix.software.ibm.com/aix/ifixes/iv86126/
    * https://aix.software.ibm.com/aix/ifixes/iv86126/
    * Installation of the ifix requires a reboot.
    **************************************************************
  

Problem conclusion

• An error in EBB context switching code causes non-EBB
  enabled applications to try and access EBB data which
  causes a segmentation fault and core dump.
  Fixed the pmsvcs code to handle the EBB context
  management correctly.
  

Temporary fix

•   *********
    * HIPER *
    *********
  

Comments

APAR Information

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

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

  IV86603 IV87180 IV87202 IV88175 IV88479

Fix information

• Fixed component name

  AIX V7.1

• Fixed component ID

  5765H4000

Applicable component levels

• R710 PSY U862950

     UP16/10/25 I 1000 Ž