IJ52948: KERNEL-CRASH IN SCALE 5.2.1.1 - GENERAL PROTECTION FAULT

APAR status

• Closed as program error.

Error description

• Kernel-Crash in Scale 5.2.1.1 - general protection fault and
  system crash.The crash happens due to a memory corruption after
  mounting a gpfs filesystem.Sometimes this happens during a
  filesystem mount and sometimes a little while after.
  

Local fix

Problem summary

• Kernel-Crash in Scale 5.2.1.1 - general protection fault and
  system crash.The crash happens due to a memory corruption after
  mounting a gpfs filesystem.Sometimes this happens during a
  filesystem mount and sometimes a little while after.
  

Problem conclusion

• Benefits of the solution:
  Fixed the code so the memory corruption is no longer seen.
  
  Work Around:
  None
  
  Problem trigger:
  We do not need any particular kernel version. For example the
  customer that hit this issue was running
  4.18.0-553.16.1.el8_10.x86_64. While I have reproduced this on a
  6.4 kernel.The length of the fstab entry should be in a sweet
  spot. What this means that is the memory is allocated from the
  slab cache which have fixed sizes.This means we may have some
  extra room in the memory allocated to us till we reach the
  object boundary and we will not have any corruption till we
  cross this boundary.The kernel slabs are of object sizes: 8, 16,
  32, 64, 96, 128, 192, 256, 512 and so on ..For the problem to
  appears, we need an fstab entry in which, after the
  gpfsdev=fsname options, there are a sizeable number of
  characters and options. This leads us to write a larger size
  then what we requested.
  
  Symptom:
  Memory corruption and subsequent crash
  
  Platforms affected:
  Linux Only
  
  Functional Area affected:
  Scale core
  
  Customer Impact:
  High Importance
  

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 STD

• Fixed component ID

  5737F33AP

Applicable component levels