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Looping lock manager can lead to NFS outage or system panic on ONTAP 9

Last Updated:

Applies to

  • ONTAP 9
  • NFS


  • Clients see NFSv4 mount failures; SetclientID ops fail with nfs4err_delay.
  • System panic with panic string similar to the following: 
    • Panic string: process on cpu19 hung (wafl_exempt12) for 5001 milliseconds!
  • A defect was introduced in the lock manager that can be triggered by qtree create operations, disabling oplocks operations, aggregate relocation, sendhome operations, volume moves, node shutdowns, and during ONTAP upgrade. 
  • This includes upgrading to an ONTAP version where the fix is present.
  • The lock manager enters a lock recovery loop that starves the system of resources until:
    • NFS service ceases to respond to clients or
    • The system panics
  • This is being tracked by BUG 1168841


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