general protection fault on gfs2:gfs2_drop_inode after GFS2 withdrawal

Issue

• A general protection fault on gfs2:gfs2_drop_inode after GFS2 withdrawal led to a kernel panic:

  general protection fault: 0000 [1] SMP 
  last sysfs file: /class/iscsi_session/session2/targetname
  CPU 0 
  Modules linked in: lock_nolock nfsd exportfs nfs_acl auth_rpcgss mpt2sas mptctl ipmi_devintf ipmi_si ipmi_msghandler dell_rbu lock_dlm gfs2 dlm configfs dm_switch(U) lockd sunrpc xt_tcpudp xt_state ip_conntrack nfnetlink xt_multiport iptable_filter ip_tables ip6table_filter ip6_tables x_tables be2iscsi ib_iser rdma_cm ib_cm iw_cm ib_sa ib_mad ib_core ib_addr iscsi_tcp bnx2i cnic ipv6 xfrm_nalgo crypto_api uio cxgb3i libcxgbi cxgb3 8021q libiscsi_tcp libiscsi2 scsi_transport_iscsi2 scsi_transport_iscsi ext3 jbd dm_mirror dm_multipath scsi_dh video backlight sbs power_meter i2c_ec i2c_core dell_wmi wmi button battery asus_acpi acpi_memhotplug ac parport_pc lp parport joydev tpm_tis tpm i5k_amb sg tpm_bios bnx2 serio_raw hwmon ide_cd i5000_edac edac_mc cdrom pcspkr dm_raid45 dm_message dm_region_hash dm_log dm_mod dm_mem_cache ata_piix libata shpchp mptsas mptscsih mptbase scsi_transport_sas sd_mod scsi_mod ext4 jbd2 crc16 uhci_hcd ohci_hcd ehci_hcd
  Pid: 6912, comm: nfsd Tainted: G     --------------------    2.6.18-348.6.1.el5 #1
  RIP: 0010:[<ffffffff8877a2d3>]  [<ffffffff8877a2d3>] :gfs2:gfs2_drop_inode+0x1c/0x2f
  RSP: 0018:ffff8102132876c8  EFLAGS: 00010206
  RAX: 09210a0d73696874 RBX: fffffffffffffffb RCX: 0000000000000001
  RDX: ffffffff8877a2b7 RSI: ffffffff8032f2d0 RDI: ffff8102053af650
  RBP: 00000000fffffffb R08: ffff81000001b600 R09: ffff810205356370
  R10: ffff810207ef1000 R11: ffffffff8877a2b7 R12: 0000000000b91ff0
  R13: ffff810207ef1000 R14: 0000000000000008 R15: 0000000000000000
  FS:  00002b6f968d56e0(0000) GS:ffffffff80436000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
  CR2: 0000000019622020 CR3: 0000000206ae4000 CR4: 00000000000006e0
  Process nfsd (pid: 6912, threadinfo ffff810213286000, task ffff81022660b0c0)
  Stack:  ffffffff8876c453 0000000000b91ff0 0000000000000000 ffff810205356370
  0000000000000000 ffff810204f560c0 ffff81020590c978 0000000000000000
  ffff810206eed408 0000000000000000 ffffffff88765070 ffff810206eed408
  Call Trace:
  [<ffffffff8000dadf>] permission+0x81/0xc8
  [<ffffffff8000f766>] generic_permission+0x52/0xca
  [<ffffffff80022f0b>] d_alloc+0x176/0x1ab
  [<ffffffff8003720a>] __lookup_hash+0x10b/0x130
  [<ffffffff800ed7b0>] lookup_one_len+0x53/0x61
  [<ffffffff800471df>] try_to_wake_up+0x472/0x484
  [<ffffffff8008d87a>] __wake_up_common+0x3e/0x68
  [<ffffffff8008ec4e>] dequeue_task+0x18/0x37
  [<ffffffff80063002>] thread_return+0x62/0xfe
  [<ffffffff8003566c>] vfs_readdir+0x77/0xa9
  [<ffffffff80064624>] __down_read+0x12/0x92
  [<ffffffff8005dfc1>] child_rip+0xa/0x11
  [<ffffffff8005dfb7>] child_rip+0x0/0x11