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IV56171: DEADLOCK IN JFS2 INTERNAL SNAPSHOT CODE CAN CAUSE HANG APPLIES TO AIX 7100-04

A fix is available

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • A dead lock can occur when working with internal jfs2
    shapshots
    As a result commands on the associated jfs2 filesystem
    can hang.
    Both kernel stacks involved with dead lock will contain
    the function
    siWriterReadSMap with stacks similar to:
    
    (0)> f 190
    pvthread+00BE00 STACK:
    [000E47F8]e_block_thread+000298 ()
    [000E5368]e_sleep_thread+0000E8 (??, ??, ??)
    [002A76D8]bmAssign+000778 (??, ??, ??, ??, ??, ??)
    [002A6960]bmRead+0000A0 (??, ??, ??, ??, ??, ??)
    [00303BD4]xtSearch+0005D4 (??, ??, ??, ??, ??)
    [002C4F88]siWriterReadSMap+000348 (F10001023D4CA880,
    0000000001ACC0A0,0FFFFFFFF4FA7B48, 0000000000000000)
    [002C4720]siCOWLookupSMap+000060 (??, ??, ??, ??, ??)
    [002CCC70]siCOW+000270 (??, ??)
    [002BBB9C]j2PagerService+00051C (??)
    [002B7954]j2PagerThread+0001F4 (??)
    [00387774]threadentry+000094 (??, ??, ??, ??)
    [kdb_read_mem] no real storage @ FFFFFFFFFFF8D30
    
    and
    0> f 81
    [00574454]complex_lock_sleep_ppc+0001D4
    (0000000000574454,
    8000000000001032,
       0000000088024024, 0FFFFFFFF42B7670 [??])
    [005763C0]lock_write_ppc+0001A0 (??)
    [002C5048]siWriterReadSMap+000408 (F10001023D4CA880,
    00000000032C8BA0,
       0FFFFFFFF42B7B48, 0000000000000000)
    [002C4720]siCOWLookupSMap+000060 (??, ??, ??, ??, ??)
    [002CCC70]siCOW+000270 (??, ??)
    [002BBB9C]j2PagerService+00051C (??)
    [002B7954]j2PagerThread+0001F4 (??)
    [00387774]threadentry+000094 (??, ??, ??, ??)
    [kdb_read_mem] no real storage @ FFFFFFFFFFF8D30
    
    Code changes in IV29780 with abstract:
    Deadlock hang in snapshot code doing chdir and remove
    operations
    
    causes the race condition which can lead to this deadlock
    

Local fix

  • Work around is to use external snapshot instead of
    internal
    snapshots
    

Problem summary

  • Database begins blocking on writes. Slowly brings IO to a stop.
    

Problem conclusion

  • Change locking serialization
    

Temporary fix

Comments

  • 6100-07 - use AIX APAR IV58198
    6100-08 - use AIX APAR IV46121
    6100-09 - use AIX APAR IV56153
    6100-09 - use AIX APAR IV56153
    6100-09 - use AIX APAR IV56153
    7100-01 - use AIX APAR IV57482
    7100-02 - use AIX APAR IV56225
    7100-03 - use AIX APAR IV56142
    7100-04 - use AIX APAR IV56171
    

APAR Information

  • APAR number

    IV56171

  • Reported component name

    AIX V7.1

  • Reported component ID

    5765H4000

  • Reported release

    710

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Submitted date

    2014-03-03

  • Closed date

    2014-03-03

  • Last modified date

    2016-05-10

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

    IV46121

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

    U871189

Fix information

  • Fixed component name

    AIX V7.1

  • Fixed component ID

    5765H4000

Applicable component levels

  • R710 PSY U871189

       UP15/11/22 I 1000

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Document Information

Modified date:
10 May 2016