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LI81243: Segfaults/hangs in OpenMP reductions

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APAR status

  • Closed as program error.

Error description

  • In case of target teams with reduction
is nested in a parallel construct,
there can be multiple threads
allocating/freeing remote buffers
simultaneously. However, the use of
remote buffer allocator/deallocator is
not synchronized and data-race happens,
which results in the buffer list being
corrupted and therefore, the
seg-faults/hangs.

Local fix

  • Use the OpenMP runtime with the fix

Problem summary

  • USERS AFFECTED:
Users who have target teams with reduction nested in a parallel
construct are affected by this issue.

PROBLEM DESCRIPTION:
In case of target teams where reduction is nested in a parallel
construct,
there can be multiple threads allocating/freeing remote buffers
simultaneously.
However, the use of remote buffer allocator/deallocator is not
synchronized and data-race happens,
which results in the buffer list being corrupted and therefore,
the seg-faults/hangs.

Problem conclusion

  • The compiler has been fixed.

Temporary fix

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    LI81243
    • 

  • Reported component name
    XL FORTRAN LINU
    • 

  • Reported component ID
    5725C7510
    • 

  • Reported release
    G11
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt / Xsystem
    • 

  • Submitted date
    2020-02-04
    • 

  • Closed date
    2020-03-11
    • 

  • Last modified date
    2020-03-11
    • 





    

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

    • 

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

    • 



Fix information


    

  • Fixed component name
    XL FORTRAN LINU
    • 

  • Fixed component ID
    5725C7510
    • 



Applicable component levels


    








      
              
                            

              

              [{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSAT4T","label":"XL Fortran for Linux"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"G11","Edition":"","Line of Business":{"code":"LOB57","label":"Power"}}]
              

                          

          
 
        

      

    

      

        

          

            
Document Information


            

            


                        

            Modified date:
            

            11 March 2020
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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