IT29123: Queue manager process suffers deadlock when handling memory exception (SIGBUS)

APAR status

• Closed as program error.

Error description

• Queue manager process suffers a deadlock when handling a memory
  exception, generating signal SIGBUS. The SIGUSR2 FDCs generated
  show one or more MQ threads with the following O/S Call Stack.
  
  O/S Call Stack for current thread
  
  /opt/mqm/lib64/libmqmcs.so'xcsPrintStackForCurrentThread+0xe8
  ...
  /opt/mqm/lib64/libmqmcs.so'signalHandlerInternal+0x3c
  /opt/mqm/lib64/libmqmcs.so'PrepareDumpAreas+0x140
  /opt/mqm/lib64/libmqmcs.so'xcsFFSTFn+0x3398
  /opt/mqm/lib64/libmqmcs.so'xcsFFSTSFn+0x1dc
  /opt/mqm/lib64/libmqmcs.so'xehProduceDebugInfo+0x194
  /opt/mqm/lib64/libmqmcs.so'xehAsySignalMonitor+0x1350
  ...
  /lib/sparcv9/libc.so.1'_lwp_start+0x0 [0xffffffff4c44931c]
  
  The stack trace generated for the affected process contains the
  following at
  the top of the stack.
  
  lwp_park (0, 0, 0)
  malloc (1e0, ffffffff4c591a50, 9a50, ffffffff4c588000, 1a13ec,
  9800) + 50
  xcsGetMemFn (a, 1002e4e80, 2, 4, ffffffffffffffff,
  ffffffff6feba398) + 22c
  xcsBuildDumpPtrFmt (ffffffff6feba398, 1, ffffffff0ace6090,
  100000000, 1000, 0) + 1f0
  xehExceptionHandler (a, ffffffff6feba9d0, ffffffff6feba6d0, 0,
  0, 0) + 19c
  __sighndlr (a, ffffffff6feba9d0, ffffffff6feba6d0,
  ffffffff0a90d350, 0, ffffffff4c588000) + c
  call_user_handler (ffffffff78613240, ffffffff6feba9d0, 7e27f857,
  fffffff0, 0, a) + 364
  sigacthandler (a, ffffffff6feba9d0, ffffffff6feba6d0, 14c0c4,
  ffffffff4c588000, a) + 5c
  --- called from signal handler with signal 10 (SIGBUS) ---
  ...
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  All users of MQ
  
  
  Platforms affected:
  AIX, HP-UX Itanium, Linux on Power, Linux on S390, Linux on
  x86-64, Linux on zSeries, Solaris SPARC, Solaris x86-64, IBM
  iSeries, Linux on x86
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  When handling the SIGBUS signal, MQ called malloc resulting in a
  potential hang.
  

Problem conclusion

• The MQ code which handles SIGBUS signal has been modified to
  resolve the problem.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.0 LTS   9.0.0.8
  v9.1 CD    9.1.3
  v9.1 LTS   9.1.0.3
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

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

  IBM MQ BASE M/P

• Fixed component ID

  5724H7261

Applicable component levels