abrt version: 2.0.1
architecture:   x86_64
cmdline:        ro root=UUID=ac977577-24ab-4b6a-af31-2af93d2ceb88 rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=fr-pc rhgb quiet
component:      kernel
kernel:         2.6.38.8-32.fc15.x86_64
kernel_tainted: 128
os_release:     Fedora release 15 (Lovelock)
package:        kernel
reason:         BUG: unable to handle kernel NULL pointer dereference at 0000000000000078
reported_to:    kerneloops: URL=http://submit.kerneloops.org/submitoops.php
time:           Sun Jun 26 14:17:10 2011

backtrace:
:BUG: unable to handle kernel NULL pointer dereference at 0000000000000078
:IP: [<ffffffff81211486>] elv_may_queue+0x10/0x1f
:PGD 0 
:Oops: 0000 [#1] SMP 
:last sysfs file: /sys/devices/pci0000:00/0000:00:1d.0/usb2/idVendor
:CPU 1 
:Modules linked in: nls_utf8 udf crc_itu_t fuse sunrpc cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables snd_hda_codec_hdmi iwlagn snd_hda_codec_realtek snd_hda_intel iwlcore snd_hda_codec snd_hwdep mac80211 snd_seq snd_seq_device microcode uvcvideo snd_pcm jme i2c_i801 cfg80211 videodev v4l2_compat_ioctl32 jmb38x_ms iTCO_wdt iTCO_vendor_support joydev intel_ips serio_raw mii snd_timer snd memstick rfkill soundcore snd_page_alloc wmi ipv6 btrfs zlib_deflate libcrc32c sdhci_pci sdhci mmc_core uas usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video
:Pid: 1545, comm: umount Not tainted 2.6.38.8-32.fc15.x86_64 #1 CLEVO Co.                        S3100                            /S3100                            
:RIP: 0010:[<ffffffff81211486>]  [<ffffffff81211486>] elv_may_queue+0x10/0x1f
:RSP: 0018:ffff88022eb2ba98  EFLAGS: 00010096
:RAX: 0000000000000000 RBX: ffff880231900000 RCX: 0000000000000010
:RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880231900000
:RBP: ffff88022eb2ba98 R08: 0000000000000000 R09: ffff88023170e720
:R10: ffffc90000c11000 R11: 0000000000000000 R12: ffff88022eb2bb40
:R13: 0000000000000000 R14: ffff88023170e720 R15: 0000000000000001
:FS:  00007ff64cb73820(0000) GS:ffff8800bb080000(0000) knlGS:0000000000000000
:CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
:CR2: 0000000000000078 CR3: 000000020df2a000 CR4: 00000000000006e0
:DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
:DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
:Process umount (pid: 1545, threadinfo ffff88022eb2a000, task ffff88020df62e60)
:Stack:
: ffff88022eb2baf8 ffffffff81215ba2 ffff88022eb2bab8 0000000000000000
: 000000100000063c 0000000000000000 000000000000000a ffff880231900000
: ffff88022eb2bb40 0000000000000000 ffff88023170e720 0000000000000000
:Call Trace:
: [<ffffffff81215ba2>] get_request+0x33/0x262
: [<ffffffff8121676a>] get_request_wait+0x35/0x193
: [<ffffffff810b07a4>] ? __call_rcu+0x123/0x12c
: [<ffffffff81216907>] blk_get_request+0x3f/0x6e
: [<ffffffff812fc861>] scsi_execute+0x41/0x146
: [<ffffffff812fca02>] scsi_execute_req+0x9c/0xce
: [<ffffffff812f8a9c>] ioctl_internal_command.constprop.1+0x6b/0x163
: [<ffffffff812f8bed>] scsi_set_medium_removal+0x59/0x94
: [<ffffffff8130b225>] sr_lock_door+0x20/0x22
: [<ffffffff8132c475>] cdrom_release+0x195/0x205
: [<ffffffff810806d9>] ? smp_call_function_many+0x1bd/0x1dc
: [<ffffffff8104127e>] ? should_resched+0xe/0x2d
: [<ffffffff81474408>] ? _cond_resched+0xe/0x22
: [<ffffffff8130a1b9>] sr_block_release+0x30/0x4d
: [<ffffffff81149aa2>] __blkdev_put+0xc6/0x179
: [<ffffffff81149c59>] blkdev_put+0x104/0x10c
: [<ffffffff81122f69>] kill_block_super+0x65/0x6a
: [<ffffffff811231a5>] deactivate_locked_super+0x26/0x4b
: [<ffffffff81123d0e>] deactivate_super+0x37/0x3b
: [<ffffffff8113863c>] mntput_no_expire+0xcc/0xd1
: [<ffffffff81139073>] sys_umount+0x2ac/0x2da
: [<ffffffff81009bc2>] system_call_fastpath+0x16/0x1b
:Code: 1f 44 00 00 48 8b 47 18 48 8b 00 48 8b 40 70 48 85 c0 74 05 48 89 f7 ff d0 5d c3 55 48 89 e5 0f 1f 44 00 00 48 8b 47 18 48 8b 00 
:RIP  [<ffffffff81211486>] elv_may_queue+0x10/0x1f
: RSP <ffff88022eb2ba98>

comment:
:I have a USB optical drive.
:
:This happens everytime I unplug its USB cables.

event_log:
:2011-06-26-14:18:50> Submitting oops report to http://submit.kerneloops.org/submitoops.php
:2011-06-26-14:19:11  Kernel oops report was uploaded