BUG: unable to handle kernel NULL pointer dereference at 00000004
IP: [<c1397961>] sd_revalidate_disk+0x21/0x290
*pde = 7e89f067 
Oops: 0000 [#1] SMP 
Modules linked in: ums_realtek(-) nls_iso8859_1 nls_cp437 vfat fat snd_hrtimer parport_pc dm_crypt ppdev bnep rfcomm bluetooth binfmt_misc joydev snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep dell_laptop snd_pcm compal_laptop dcdbas snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq lib80211_crypt_tkip uvcvideo videodev snd_timer snd_seq_device snd psmouse serio_raw wl(P) soundcore snd_page_alloc lib80211 mac_hid lp parport uas i915 drm_kms_helper r8169 drm i2c_algo_bit usb_storage video [last unloaded: ums_realtek]

Pid: 2697, comm: blkid Tainted: P           O 3.2.0-17-generic #26-Ubuntu Dell Inc. Inspiron 1012/0P9MDV
EIP: 0060:[<c1397961>] EFLAGS: 00010286 CPU: 1
EIP is at sd_revalidate_disk+0x21/0x290
EAX: 00000000 EBX: 00000000 ECX: 00000001 EDX: c1397940
ESI: ec0cb060 EDI: ec0cb000 EBP: ec019d48 ESP: ec019d28
 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
Process blkid (pid: 2697, ti=ec018000 task=eddbbf20 task.ti=ec018000)
Stack:
 c11494c3 f3bb2c00 00000000 00000002 00000001 00000000 ec0cb060 ec0cb000
 ec019db4 c118bbf2 00000ba3 c1382e37 c108275a f8048400 ec019d68 c135ea94
 ec019d78 c1382e24 edcd1600 ec0cb060 00000000 f3bb2c00 ec0c8800 ffffff85
Call Trace:
 [<c11494c3>] ? iput+0x23/0x40
 [<c118bbf2>] rescan_partitions+0x82/0x350
 [<c1382e37>] ? scsi_device_put+0x47/0x50
 [<c108275a>] ? module_refcount+0x7a/0x90
 [<c135ea94>] ? put_device+0x14/0x20
 [<c1382e24>] ? scsi_device_put+0x34/0x50
 [<c139524f>] ? sd_open+0xff/0x1d0
 [<c1163436>] __blkdev_get+0x266/0x3c0
 [<c11635d7>] blkdev_get+0x47/0x180
 [<c1163760>] blkdev_open+0x50/0x70
 [<c112fece>] __dentry_open+0x25e/0x310
 [<c1163710>] ? blkdev_get+0x180/0x180
 [<c113044a>] vfs_open+0x3a/0x50
 [<c1131349>] nameidata_to_filp+0x39/0x40
 [<c113e6d7>] do_last+0x367/0x660
 [<c113fa04>] path_openat+0xa4/0x350
 [<c113fdc1>] do_filp_open+0x31/0x80
 [<c12a2568>] ? strncpy_from_user+0x38/0x70
 [<c114b353>] ? alloc_fd+0xa3/0xe0
 [<c1131431>] do_sys_open+0xe1/0x1f0
 [<c10a0652>] ? audit_syscall_exit+0x192/0x1c0
 [<c113156e>] sys_open+0x2e/0x40
 [<c15737c4>] syscall_call+0x7/0xb
 [<c1570000>] ? iommu_prepare_identity_map+0x17a/0x1e8
Code: 74 26 00 8d bc 27 00 00 00 00 55 89 e5 83 ec 20 89 5d f4 89 75 f8 89 7d fc 3e 8d 74 26 00 8b 98 e8 01 00 00 89 c7 a1 40 6b 9b c1 <8b> 73 04 c1 e8 15 83 e0 07 83 f8 03 0f 87 fa 01 00 00 8b 86 94 
EIP: [<c1397961>] sd_revalidate_disk+0x21/0x290 SS:ESP 0068:ec019d28
CR2: 0000000000000004
---[ end trace 07e3625557486839 ]---