IV68324: DEADLOCK IN PRUBLOCKSEGATTACH / PRGETEREF WHILE EXECING

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Deadlock with stack similar to:
  
  [000F21D8]e_block_thread+000298 ()
  [000F2D48]e_sleep_thread+0000E8 (??, ??, ??)
  [000ECDCC]prUblockSegAttach+00006C (??, ??)
  [0043CD34]prGetPsinfo+0005F4 (??, ??, ??)
  [0043CEE8]prReadPsinfo+000168 (??, ??, ??, ??, ??, ??,
  ??, ??)
  [00439B78]procfsRdwr+0001D8 (??, ??, ??, ??, ??, ??, ??,
  ??)
  [006009F4]vnop_rdwr+000814 (??, ??, ??, ??, ??, ??, ??,
  ??)
  [00619AB4]vno_rw+0000B4 (??, ??, ??, ??, ??)
  [005AF020]rwuio+000100 (??, ??, ??, ??, ??, ??)
  [005AF368]rdwr+000188 (??, ??, ??, ??, ??, ??)
  [005AEEDC]keread+00013C (??, ??, ??, ??)
  [00003888]mfspurr_sc_flih01+0000E4 ()
  [kdb_get_virtual_memory] no real storage @
  FFFFFFFFFFF31D0
  [90000000002E830]090000000002E830 ()
  [kdb_read_mem] no real storage @ FFFFFFFFFFF9080
  
  (0)> f 1739
  pvthread+06CB00 STACK:
  [00599958]slock+000598 (000000000000B658,
  8000000000009032 [??])
  [00009558].simple_lock+000058 ()
  [000EE2D0]prGetEref+000070 (??)
  [0043CE10]prReadPsinfo+000090 (??, ??, ??, ??, ??, ??,
  ??, ??)
  [00439B78]procfsRdwr+0001D8 (??, ??, ??, ??, ??, ??, ??,
  ??)
  [006009F4]vnop_rdwr+000814 (??, ??, ??, ??, ??, ??, ??,
  ??)
  [00619AB4]vno_rw+0000B4 (??, ??, ??, ??, ??)
  [005AF020]rwuio+000100 (??, ??, ??, ??, ??, ??)
  [005AFA60]fp_rdwr+000160 (??, ??, ??, ??, ??, ??, ??, ??)
  [005B03D4]fp_read+000034 (??, ??, ??, ??, ??, ??)
  [053EBB88]amf_get_psinfo+000160 (??, ??)
  [053EBC7C]amf_s_proff_pid_monitor+000068 (??)
  [053EB7EC]amf_prexec_hook+000088 (??, ??, ??)
  [000E9188]prochcall+000268 (??, ??, ??, ??)
  [0048FA58]execvex_common+0022D8 (??, ??, ??, ??, ??)
  [00492F8C]execve+0000A8 ()
  

Local fix

Problem summary

• Threads will deadlock in prUblockSegAttach  and prGetEref.
  Here one thread will wait for pv_xproc_synch event to happen
  after holding the prGetEref lock and other thread will wait for
  prGetEref lock before posting pv_xproc_synch.
  
  Thread1 :
   000F21D8 e_block_thread+000298 ()
   000F2D48 e_sleep_thread+0000E8 (??, ??, ??)
   000ECDCC prUblockSegAttach+00006C (??, ??)
   0043CD34 prGetPsinfo+0005F4 (??, ??, ??)
   0043CEE8 prReadPsinfo+000168 (??, ??, ??, ??, ??, ??,
  ??, ??)
   00439B78 procfsRdwr+0001D8 (??, ??, ??, ??, ??, ??, ??,
  ??)
   006009F4 vnop_rdwr+000814 (??, ??, ??, ??, ??, ??, ??,
  ??)
   00619AB4 vno_rw+0000B4 (??, ??, ??, ??, ??)
   005AF020 rwuio+000100 (??, ??, ??, ??, ??, ??)
   005AF368 rdwr+000188 (??, ??, ??, ??, ??, ??)
   005AEEDC keread+00013C (??, ??, ??, ??)
   00003888 mfspurr_sc_flih01+0000E4 ()
   kdb_get_virtual_memory  no real storage @
  FFFFFFFFFFF31D0
   90000000002E830 090000000002E830 ()
   kdb_read_mem  no real storage @ FFFFFFFFFFF9080
  
  Thread2 :
  pvthread+06CB00 STACK:
   00599958 slock+000598 (000000000000B658,
  8000000000009032  ?? )
   00009558 .simple_lock+000058 ()
   000EE2D0 prGetEref+000070 (??)
   0043CE10 prReadPsinfo+000090 (??, ??, ??, ??, ??, ??,
  ??, ??)
   00439B78 procfsRdwr+0001D8 (??, ??, ??, ??, ??, ??, ??,
  ??)
   006009F4 vnop_rdwr+000814 (??, ??, ??, ??, ??, ??, ??,
  ??)
   00619AB4 vno_rw+0000B4 (??, ??, ??, ??, ??)
   005AF020 rwuio+000100 (??, ??, ??, ??, ??, ??)
   005AFA60 fp_rdwr+000160 (??, ??, ??, ??, ??, ??, ??, ??)
   005B03D4 fp_read+000034 (??, ??, ??, ??, ??, ??)
   053EBB88 amf_get_psinfo+000160 (??, ??)
   053EBC7C amf_s_proff_pid_monitor+000068 (??)
   053EB7EC amf_prexec_hook+000088 (??, ??, ??)
   000E9188 prochcall+000268 (??, ??, ??, ??)
   0048FA58 execvex_common+0022D8 (??, ??, ??, ??, ??)
   00492F8C execve+0000A8 ()
  

Problem conclusion

• Avoid dead lock by properly serialize the opertion of holding
  the lock and posting event.
  

Temporary fix

Comments

APAR Information

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

  IV65814

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

Fix information

• Fixed component name

  AIX V7.1

• Fixed component ID

  5765H4000

Applicable component levels

• R710 PSY U863867

     UP15/11/22 I 1000

PTF to Fileset Mapping

• U863867 bos.mp64 7.1.4.0

• U863867 bos.mp64 7.1.4.0