IJ53693: ZERO'ED OUT MEMORY PAGES WHEN DIRECTIO PAGES ARE SWAPPED

APAR status

• Closed as program error.

Error description

• zero'ed out memory pages  when directio pages are swapped
  

Local fix

• pin the db2 pages
  

Problem summary

• Issuing a direct i/o read system call to GPFS and having the
  data buffer reside in Linux shared memory and having the
  corresponding memory pages swapped out can lead to loss of data.
  

Problem conclusion

• This problem is fixed in 5.1.9.9
  To see all Spectrum Scale APARs and their respective
  Fix solutions refer to page: 
  https://public.dhe.ibm.com/storage/spectrumscale/spectrum_scale
  _apars.html
  
  Benefits of the solution:
  The described problem will no longer occur.
  
  Work Around:
  Not using Linux shared memory, or preventing swapping would
  avoid this problem.
  
  Problem trigger:
  All of these conditions need to be met in order for this problem
  to occur: An application is using Linux shared memory, is
  issuing a direct i/o read request into that memory and that
  memory is being swapped out.
  
  Symptom:
  Unexpected Results/Behavior
  
  Platforms affected:
  ALL Linux OS environments
  
  Functional Area affected:
  All Scale Users
  
  Customer Impact:
  HiPER
  

Temporary fix

Comments

APAR Information

• 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

  SPEC SCALE DME

• Fixed component ID

  5737F34AP

Applicable component levels