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IT28414: DB2 MIGHT CRASH IN SQLOFMBLKEX->SQLO_MEM_POOL::MEMTREEPUT WITH "CORRUPT POOL FREE TREE NODE" ERROR MESSAGE IN DB2DIAG.LOG

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APAR status

  • Closed as program error.

Error description

  • Db2 might crash when freeing memory of certain sizes. Trap file
    & db2diag.log will show the following functions on the top of
    the stack:
    
    SQLO_MEM_POOL::diagnoseMemoryCorruptionAndCrash
    SQLO_MEM_POOL::MemTreePut
    sqlofmblkEx
    
    and an error message reported to db2diag.log will indicate a
    corrupt pool free tree:
    
    FUNCTION: DB2 UDB, SQO Memory Management,
    sqloDiagnoseFreeBlockFailure, probe:999
    MESSAGE : Memory validation failure, diagnostic file dumped.
    DATA #1 : String, 28 bytes
    Corrupt pool free tree node.
    
    Problem is specific to Db2 11.1 Mod 4 FP4 (also iFix 001)
    environments and is more likely to happen if DB_MEM_THRESH is
    *not* set to 100 (which is the recommended value). One of the
    code paths affected is backup - at the end of backup instance
    might crash with the following functions on the top of the
    stack:
    
    SQLO_MEM_POOL::diagnoseMemoryCorruptionAndCrash
    SQLO_MEM_POOL::MemTreePut
    sqlofmblkEx
    sqluxFreeAllMem
    sqlubcka
    

Local fix

  • Verify DB_MEM_THRESH for the database and set it to 100 if the
    current value is different, which should greatly reduce the risk
    of hitting the error.
    
    For BACKUP scenarios, use a different size backup buffer e.g. 2
    buffers more (or less) than the current value, which triggered
    the crash.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All users                                                    *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 Version 11.1 Mod 4 Fix pack 5                 *
    ****************************************************************
    

Problem conclusion

  • Problem first fixed in DB2 Version 11.1 Mod 4 Fix pack 5
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT28414

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2019-03-12

  • Closed date

    2019-07-10

  • Last modified date

    2019-07-10

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

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

    424AC6Ÿ IT30792

Modules/Macros

  • engn_sqo
    

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RB10 PSN

       UP

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Document Information

Modified date:
10 July 2019