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IT27178: TIMING ISSUE IN PACKAGE CACHE WORKSPACE MAY CAUSE PANIC

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • There is a timing issue where there is a brief moment in time
    that the state of a sibling entry in package cache workspace can
    be set to a particular state outside of latch control, so the
    entry might be reused or freed up from the lru lists in the
    cache by someone else, as a result, panic may happen due to
    memory corruption.
    
    The stack can be vary:
    
    Stack 1:
     sqle_panic
     sqloCrashOnCriticalMemoryValidationFailure
     SQLO_MEM_POOL::diagnoseMemoryCorruptionAndCrash
     sqloDiagnoseFreeBlockFailure
     sqlofmblkEx
     sqlra_sqlW_mem_free_sibling_list
     sqlra_sqlW_mem_freespace
     sqlra_sqlW_check_for_cleanup
     sqlra_sqlW_get_dynamic_section_new
     sqlra_load_var
     sqlra_get_var
     sqlrr_execimmd
     sqlrr_execimmd
    
    Stack 2:
    
    PID     : 1704972              TID : 79974          PROC :
    db2sysc 0
    INSTANCE: db2inst1             NODE : 000           DB   :
    SAMPLE
    APPHDL  : 0-360                APPID:
    *LOCAL.db2inst1.180203112927
    AUTHID  : DB2INST1             HOSTNAME: MYHOST
    EDUID   : 79974                EDUNAME: db2agent (SAMPLE) 0
    FUNCTION: DB2 UDB, SQO Latch Tracing,
    SQLO_SLATCH_CAS64::getConflictComplex, probe:210
    MESSAGE :
    ZRC=0x870F00FD=-2029059843=SQLO_SLATCH_ERROR_HELDS_WITH_SHARED_W
    AITER
              "A latch with X starvation policy should StarveX latch
    should not be held shared and have a shared waiter."
    CALLED  : OS, -, unspecified_system_function
    DATA #1 : String, 13 bytes
    invalid latch
    DATA #2 : File name, 16 bytes
    sqloLatchCAS64.C
    DATA #3 : Source file line number, 8 bytes
    592
    DATA #4 : Codepath, 8 bytes
    0
    DATA #5 : String, 136 bytes
    0xFAB0A00020002EA0: {
       held X: 0
       reserved for X: 0
       shared holders: 11936
       firstSharIndex: 0x200
       firstExclIndex: 0x1D5850
    }
    DATA #6 : LatchMode, PD_TYPE_LATCH_MODE, 8 bytes
    0x10000 (SQLO_LATCH_MODE_EXCLUSIVE)
    DATA #7 : String, 397 bytes
    {
       state         = 0xFAB0A00020002EA0
                     = {
                           held X: 0
                           reserved for X: 0
                           shared holders: 11936
                           firstSharIndex: 0x200
                           firstExclIndex: 0x1D5850
                       }
       starve X mode = true
       xWaitCount    = 0
       requestCount  = 0
       identity      = NO_IDENTITY (0)
    }
    DATA #8 : Pointer, 8 bytes
    0x0a00020002ede448
    DATA #9 : Hexdump, 16 bytes
    0x0A00020002EDE448 : FAB0 A000 2000 2EA0 0A00 0200 02ED E108
    .... ...........
    CALLSTCK: (Static functions may not be resolved correctly, as
    they are resolved to the nearest symbol)
      [0] 0x090000000DC8088C
    dumpDiagInfoAndPanic__17SQLO_SLATCH_CAS64CFCPCcCUiCUlT3ClT3CiT1T
    3T7 + 0x2FC
      [1] 0x090000000CA0C814
    getConflictComplex__17SQLO_SLATCH_CAS64FCUl + 0xE8C
      [2] 0x090000000CE80D54 getConflict__17SQLO_SLATCH_CAS64FCUl +
    0x118
      [3] 0x090000000B8D9F2C
    sqlra_sqlW_mem_freespace__FP8sqlrr_cbUlPUli + 0x1C4
      [4] 0x090000000B8A561C
    sqlra_sqlW_check_for_cleanup__FP8sqlrr_cbUlP7OSSTick + 0x264
      [5] 0x090000000B899D7C
    sqlra_sqlW_get_dynamic_section_new__FP8sqlrr_cbP16sqlra_cached_v
    ar + 0x14B8
      [6] 0x090000000B89ADF8
    sqlra_load_var__FP8sqlrr_cbP16sqlra_cached_varP14SQLP_LOCK_INFOP
    b + 0xAC
      [7] 0x090000000B89AA8C sqlra_get_var__FP8sqlrr_cbiT2bPbT5 +
    0x884
      [8] 0x090000000C587808
    sqlrr_execute__FP14db2UCinterfaceP9UCstpInfo + 0x114
      [9] 0x090000000C587B10
    sqlrr_execute__FP14db2UCinterfaceP9UCstpInfo + 0x41C
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * N/A                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 v11.1 Mod4 Fixpack4.                          *
    ****************************************************************
    

Problem conclusion

  • The problem is firstly fixed on Db2 v11.1 Mod4 Fixpack4
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT27178

  • 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

    2018-12-04

  • Closed date

    2018-12-09

  • Last modified date

    2019-04-29

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

    IT24765

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

    PH11595

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RB10 PSY

       UP

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1","Edition":"","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
29 April 2019