IT19148: SIGSEGV from zmuHealthCheck during queue manager shutdown

APAR status

• Closed as program error.

Error description

• During shutdown the queue manager writes failure records in FDC
  files.
  A loss of queue manager function might be experienced, but not
  always.
  
  Details from the FDC files follow:
  
  Probe Id     :- XC130003
  Component     :- xehExceptionHandler
  Program Name      :- amqzmur0
  Arith1      :- 11 (0xb)
  Comment1     :- SIGSEGV: address not mapped(1c)
  
  MQM Function Stack
  amqzmur0
  zmuUtilityManager
  zmuShutdownPhase
  zmuHealthCheck
  xcsFFST
  
  /opt/mqm/lib64/libmqml.so 'zmuHealthCheck+0x674
  [0xffff80ff5447aef4] [Signal 11 (SEGV)]
  /opt/mqm/lib64/libmqml.so 'zmuShutdownPhase+0x2cb
  [0xffff80ff5447793b]
  /opt/mqm/lib64/libmqml.so 'zmuUtilityManager+0x1d37
  [0xffff80ff54473e67]
  /opt/mqm/bin/amqzmur0   'main+0x16b [0x40118b]
  /opt/mqm/bin/amqzmur0   '_start+0x6c [0x400ffc]
  
  
  Also Probe Id ZX103101 is seen.
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This can happen while shutting the queue manager down, and is
  rare because it is due to a rare timing condition.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  While working through a list of data blocks, an MQ internal task
  freed one of these blocks, then accessed the memory that was
  just freed.  If in that brief moment another task in the queue
  manager had been given that block, then it had written its own
  data there, and the MQ internal task just mentioned would access
  a null pointer.
  

Problem conclusion

• The IBM MQ product has been corrected so that the memory just
  freed is no longer accessed in this invalid way.  The FDC is
  therefore avoided.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.0 CD    9.0.3
  v9.0 LTS   9.0.0.2
  
  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

• R900 PSY

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