RIP nfs_free_unlinkdata でシステムがクラッシュする

Issue

• システムがクラッシュし、以下のパニックメッセージが発生します。

  Unable to handle kernel NULL pointer dereference at 00000000000000f8 RIP: 
   [<ffffffff887e44d2>] :nfs:nfs_free_unlinkdata+0xb/0x48
  PGD 7f3fcf067 PUD 7fc778067 PMD 0 
  Oops:0000 [1] SMP 
  last sysfs file:/devices/pci0000:00/0000:0:03.0/irq
  CPU 4 
  Modules linked in: cpqci(U) mptctl autofs4 nfs lockd fscache nfs_acl sunrpc dmpaa(U) vxspec(U) vxio(U) vxdmp(U) fdd(U) vxportal(U) vxfs(U) dm_mirror dm_multipath dm_mod video sbs backlight i2c_ec button battery asus_acpi acpi_memhotplug ac parport_pc lp parport sg ide_cd i2c_amd756 i2c_core lpfc serio_raw cdrom shpchp scsi_transport_fc tg3 e1000 k8_edac amd_rng edac_mc k8temp floppy hwmon pcspkr usb_storage ata_piix sata_nv libata mptsas scsi_transport_sas mptspi mptscsih scsi_transport_spi mptbase cciss sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci_hcd
  Pid:25963, comm: dagent Tainted:PF     2.6.18-53.1.14.el5 #1
  RIP:0010:[<ffffffff887e44d2>]  [<ffffffff887e44d2>] :nfs:nfs_free_unlinkdata+0xb/0x48
  ---
  Process dagent (pid:25963, threadinfo ffff8101b4c70000, task ffff8101b56b67e0)
  ---
  Call Trace:
   [<ffffffff887dba95>] :nfs:nfs_dentry_iput+0x53/0x64
   [<ffffffff8000cf9f>] dput+0xf6/0x114
   [<ffffffff800123fb>] __fput+0x16c/0x198
   [<ffffffff80023807>] filp_close+0x5c/0x64
   [<ffffffff8001d7b7>] sys_close+0x88/0xa2
   [<ffffffff80060618>] cstar_do_call+0x1b/0x65