IV35531: SEGFAULT ON OBJECT ALLOCATION IN JAVA7SR3/JAVA626SR5 WITH -XGCPO LICY:METRONOME

APAR status

• Closed as program error.

Error description

• Error Message: A SIGSEGV/GPF is received when allocating (or
  right after) a large object allocation on soft realtime
  (-Xgcpolicy:metronome on the command-line but -Xrealtime is
  not).
  .
  Stack Trace: N/A
  .
  

Local fix

• Using 64-bit jvm will likely fix the problem.
  

Problem summary

• Recently with the change of increasing the number of size
  classes in Java7SR3/Java626SR5 has exposed a bug in our existing
  code base.
  Specifically the problem is caused when attempt to allocate a
  large objects for a large size class (<TLD> 4k-64k) near the end
  of the address space.  A check at this point fails due to
  integer overflow and we allocate the object incorrectly.
  We will seg fault either immediately at that large allocation or
  on the next subsequent allocation (depends on page size).
  

Problem conclusion

• This defect will be fixed in:
  7.0.0 SR4
  6.0.1 SR5
  WRT-V3 SR4
  .
  Object allocation code has been corrected so that the checking
  code never overflows
  

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:

  IV35532

Fix information

• Fixed component name

  J9 COMMON CODE

• Fixed component ID

  620700127

Applicable component levels

• R260 PSY

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