PK91164: CRASH IN GC DUE TO STACK POINTER MISALIGNMENT

APAR status

• Closed as program error.

Error description

• Error Message: Customer reported a crash in GC due to too many
  object corruptions.After running with pd build ,Customer got
  following message -
  ***********************************************************
  panic: '/userlvl/cxia32142/src/jvm/sov/st/msc/gc_mark.c', line
  2930
  assertion failure: '!((uintptr_t)ssc % sizeof(void *))'
  
  ***********************************************************
  .
  Stack Trace: #0  0x00a957a2 in _dl_sysinfo_int80 () from
  /lib/ld-linux.so.2
  #1  0x00ad6815 in raise () from /lib/tls/libc.so.6
  
  #2  0x00ad83d1 in abort () from /lib/tls/libc.so.6
  
  #3  0xb7f8b9ee in xmPanic (ee=0xb2ac95e8,
  reason=FIRST_PANIC_CODE,
      format=0xb7fb4aa0 "'%s', line %d\nassertion failure:
  '%s'\n")
      at /userlvl/cxia32142/src/jvm/sov/xm/exc.c:224
  
  #4  0xb7efdd65 in scanThread (t=0xa989ae98, arg=0xb2ac95e8)
  
      at /userlvl/cxia32142/src/jvm/sov/st/msc/gc_mark.c:2930
  
  #5  0xb7d26ed5 in sysThreadEnumerateOver ()
  
     from /opt/IBM/WebSphere/AppServer/java/jre/pd/bin/libhpi.so
  
  #6  0xb7efe14a in scanThreads (ee=0xb2ac95e8)
  
      at /userlvl/cxia32142/src/jvm/sov/st/msc/gc_mark.c:3081
  
  #7  0xb7f0d432 in gc0_locked (ee=0xb2ac95e8,
  free_space_goal=26216
      clear_soft_refs=FALSE, target_heap=64)
  
      at /userlvl/cxia32142/src/jvm/sov/st/msc/gc_mwmain.c:4041
  
  #8  0xb7f2b87f in gc_locked (ee=0xb2ac95e8, free=262160,
  
      clear_soft_refs=FALSE, target_heap=64)
  
      at
  /userlvl/cxia32142/src/jvm/pfm/st/msc/machgc_nonsparc.c:69
  #9  0xb7f0f9cb in gc0 (ee=0xb2ac95e8, free_space_goal=262160,
  
      clear_soft_refs=FALSE, target_heap=64)
  
      at /userlvl/cxia32142/src/jvm/sov/st/msc/gc_mwmain.c:5274
  
  #10 0xb7f0ac11 in manageAllocFailure (ee=0xb2ac95e8, n=262160,
  
  target_heap=64)
  
      at /userlvl/cxia32142/src/jvm/sov/st/msc/gc_mwmain.c:2696
  
  #11 0xb7ed0217 in lockedHeapAlloc (ee=0xb2ac95e8, mptr=0x40000,
  
  n0=262160,
  
      locknflags=66, target_heap=64)
  
      at /userlvl/cxia32142/src/jvm/sov/st/msc/gc_alloc.c:2411
  
  #12 0xb7ed337e in jitLockedHeapAlloc (ee=0xb2ac95e8,
  size=262160,
      mptr=0x40000, locknflags=66)
  
      at /userlvl/cxia32142/src/jvm/sov/st/msc/gc_alloc.c:4430
  .
  

Local fix

• Compile the   JNI libraries with "-march=pentium4" with gcc4
  compiler.
  

Problem summary

• Garbage collector of 142 JVM found that the stack pointer
  for a thread is not word-aligned. On further investigation
  we found that the aplication's JNI library (libxalan-c.so
  ),which was compiled with gcc v3 ,had instructions ,which cause
  stack pointer misalignment.
  

Problem conclusion

• This defect will be fixed in:
  1.4.2 SR13-1
  .
  The problem was corrected by JVM fix 146554 .
  This fix detects the stack pointer misalignment and makes
  it word-aligned rathre then crashing .
  .
  To obtain the fix:
  Install build 20090622 or later
  

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

  JAVA(1.3/1.4 CO

• Fixed component ID

  5648C9800

Applicable component levels

• R42A PSN

     UP

• R42L PSN

     UP

• R42W PSN

     UP

• R420 PSN

     UP