IBM Support

IJ07546: KERNEL DEADLOCK CAUSED BY FASTPATHDISABLESLOW

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APAR status

  • Closed as program error.

Error description

  • There is a kernel deadlock symptom in mmap cacheFastRead
in
multiple kernel, one of which still uses regular mmap
read

Reported in:
Spectrum Scale 5.0.x on Linux x86

Known Impact:
Customer application in mmap threads hang

Verification steps:
Deadlock hang soon after app starting up

Local fix

  • Reboot OS can temporary release this deadlock contention

Problem summary

  • Deadlock when threads of one process use mmap and regular reads
on the same file if the regular read goes cached fast code path.
This problem is introducted by
'mmap optimization: add fast path for sequential reads' feature.

Problem conclusion

  • Avoid cached fast read if the file is mapped unless it is
from pagefault.

Temporary fix

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    IJ07546
    • 

  • Reported component name
    SPEC SCALE STD
    • 

  • Reported component ID
    5737F33AP
    • 

  • Reported release
    501
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt / Xsystem
    • 

  • Submitted date
    2018-07-05
    • 

  • Closed date
    2018-07-13
    • 

  • Last modified date
    2018-07-13
    • 





    

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

    • 

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

    
IJ07782
    

    • 



Fix information


    

  • Fixed component name
    SPEC SCALE STD
    • 

  • Fixed component ID
    5737F33AP
    • 



Applicable component levels


    

  • R501  PSY
       UP
    • 








      
              
                            

              

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Document Information


            

            


                        

            Modified date:
            

            13 July 2018
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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