Infinite loop while returning NFSv4 delegations to certain NAS devices on RHEL6

Solution Verified - Updated -


  • File operations on NFSv4 mounts hangs from certain NAS devices on RHEL6.1
  • There is no issues with NFSv3 from the same NAS.
  • Issue is not seen on RHEL based NFS servers.
  • SysRq shows the following trace in /var/log/messages.

    PID: 2974   TASK: ffff880854a25500  CPU: 1   COMMAND: "vim"
    #0 [ffff880847aa9a48] schedule at ffffffff814dad09
    #1 [ffff880847aa9b10] rpc_wait_bit_killable at ffffffffa0595d14 [sunrpc]
    #2 [ffff880847aa9b20] __wait_on_bit at ffffffff814dbd5f
    #3 [ffff880847aa9b70] out_of_line_wait_on_bit at ffffffff814dbe08
    #4 [ffff880847aa9be0] __rpc_wait_for_completion_task at ffffffffa0595cee [sunrpc]
    #5 [ffff880847aa9bf0] nfs4_run_open_task at ffffffffa065ee60 [nfs]
    #6 [ffff880847aa9c80] nfs4_open_recover_helper at ffffffffa0661345 [nfs]
    #7 [ffff880847aa9cc0] nfs4_open_recover at ffffffffa0661516 [nfs]
    #8 [ffff880847aa9d00] nfs4_open_delegation_recall at ffffffffa0665f57 [nfs]
    #9 [ffff880847aa9d70] __nfs_inode_return_delegation at ffffffffa067380e [nfs]
    #10 [ffff880847aa9df0] nfs_inode_return_delegation at ffffffffa0673df6 [nfs]
    #11 [ffff880847aa9e20] nfs_setattr at ffffffffa06486a8 [nfs]
    #12 [ffff880847aa9e60] notify_change at ffffffff8118e1b8
    #13 [ffff880847aa9ed0] sys_fchmodat at ffffffff811704c3
    #14 [ffff880847aa9f70] sys_chmod at ffffffff81170518
    #15 [ffff880847aa9f80] tracesys at ffffffff8100b388 (via system_call)


  • Red Hat Enterprise Linux 6
  • NFSv4 exports from a few vendors

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