Comment 2 for bug 258450

I've now seen several more instances of this crash, both during start-up and after the system has been running for some time.

When it occurs in a user session it has always killed all user input via the (PS/2-style) keyboard (not a Bluetooth keyboard). All user-space keyboard active fails with only the mouse (ironically, a Bluetooth mouse!) operating.

In addition, the GUI will fail to respond to many actions such as displaying the taskbar (I have it set to auto-hide), the shutdown/log-off/suspend/hibernate/lock menu buttons do not cause their actions to fire, and slowly the system will become unresponsive.

Even Sys-Rq key sequences fail to cause their expected actions although, if at a tty screen, the kernel sys-log will show the key-pressed were received by the kernel.

Here's the /var/log/kern.log for a mid-session crash:

kernel: [78323.255743] Unable to handle kernel NULL pointer dereference at 0000000000000020 RIP:
kernel: [78323.255752] [klist_del+0x18/0x80] klist_del+0x18/0x80
kernel: [78323.255764] PGD 56ed8067 PUD 63565067 PMD 0
kernel: [78323.255770] Oops: 0000 [2] SMP
kernel: [78323.255775] CPU 0
kernel: [78323.255778] Modules linked in: snd_usb_audio snd_usb_lib ov51x_jpeg uvcvideo isofs udf hidp hid r5u870 usbcam videodev v4l1_compat compat_ioctl32 v4l2_common videobuf_dma_sg videobuf_core tun binfmt_misc af_packet bnep rfcomm l2cap nfsd lockd nfs_acl auth_rpcgss sunrpc exportfs ipt_MASQUERADE iptable_nat nf_nat nf_conntrack_ipv4 xt_state nf_conntrack ipt_REJECT xt_tcpudp bridge kvm_intel kvm ppdev ipv6 acpi_cpufreq cpufreq_stats cpufreq_conservative cpufreq_userspace cpufreq_powersave cpufreq_ondemand freq_table sbs sbshc dock container iptable_filter ip_tables x_tables sbp2 parport_pc lp parport arc4 ecb joydev pcmcia hci_usb snd_hda_intel bluetooth snd_pcm_oss snd_mixer_oss nvidia(P) iwl3945 snd_pcm iwlwifi_mac80211 snd_page_alloc snd_hwdep snd_seq_dummy pcspkr cfg80211 snd_seq_oss evdev i2c_core sony_laptop iTCO_wdt snd_seq_midi tifm_7xx1 iTCO_vendor_support snd_rawmidi snd_seq_midi_event serio_raw video output snd_seq psmouse tifm_core button snd_timer snd_seq_device yenta_
kernel: ocket rsrc_nonstatic pcmcia_core battery ac snd shpchp pci_hotplug intel_agp soundcore dm_multipath ext3 jbd mbcache sha256_generic aes_x86_64 cbc blkcipher nls_iso8859_1 nls_cp437 vfat fat usb_storage libusual sg sr_mod sd_mod cdrom ata_piix pata_acpi dm_crypt ata_generic ohci1394 libata scsi_mod e100 mii ieee1394 ehci_hcd uhci_hcd usbcore dm_mirror dm_snapshot dm_mod thermal processor fan fbcon tileblit font bitblit softcursor fuse
kernel: [78323.255947] Pid: 9, comm: events/0 Tainted: P D 2.6.24-21-generic #1
kernel: [78323.255951] RIP: 0010:[klist_del+0x18/0x80] [klist_del+0x18/0x80] klist_del+0x18/0x80
kernel: [78323.255959] RSP: 0018:ffff81007bde5e30 EFLAGS: 00010286
kernel: [78323.255963] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffffffffffd8
kernel: [78323.255967] RDX: 0000000000000000 RSI: ffff81007bde5e30 RDI: ffff8100652aa5c0
kernel: [78323.255971] RBP: ffff8100652aa598 R08: ffff81007bde4000 R09: 0000000000000000
kernel: [78323.255974] R10: ffff810001013fe0 R11: 0000000000000001 R12: ffff8100652aa5c0
kernel: [78323.255978] R13: ffff81007dc01788 R14: ffff81007cf0eb80 R15: 0000000000000000
kernel: [78323.255983] FS: 0000000000000000(0000) GS:ffffffff805b9000(0000) knlGS:0000000000000000
kernel: [78323.255987] CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b
kernel: [78323.255991] CR2: 0000000000000020 CR3: 00000000634e4000 CR4: 00000000000026e0
kernel: [78323.255995] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
kernel: [78323.255998] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
kernel: [78323.256003] Process events/0 (pid: 9, threadinfo ffff81007bde4000, task ffff81007bdba7e0)
kernel: [78323.256006] Stack: 0000000000000000 ffff8100652aa598 ffff81007dc01780 ffffffff803bd290
kernel: [78323.256015] 0000000000000000 ffff8100652aa598 ffff81007dc01780 ffff81007dc01788
kernel: [78323.256022] 0000000000000000 ffffffff88b3eed3 0000000000000000 ffff81007dc01780
kernel: [78323.256028] Call Trace:
kernel: [78323.256047] [usbcore:device_del+0x20/0x2a0] device_del+0x20/0x2a0
kernel: [78323.256082] [bluetooth:del_conn+0x43/0x60] :bluetooth:del_conn+0x43/0x60
kernel: [78323.256103] [bluetooth:del_conn+0x0/0x60] :bluetooth:del_conn+0x0/0x60
kernel: [78323.256112] [run_workqueue+0xcc/0x170] run_workqueue+0xcc/0x170
kernel: [78323.256118] [worker_thread+0x0/0x110] worker_thread+0x0/0x110
kernel: [78323.256129] [worker_thread+0x0/0x110] worker_thread+0x0/0x110
kernel: [78323.256138] [worker_thread+0xa3/0x110] worker_thread+0xa3/0x110
kernel: [78323.256152] [<ffffffff80253a20>] autoremove_wake_function+0x0/0x30
kernel: [78323.256167] [worker_thread+0x0/0x110] worker_thread+0x0/0x110
kernel: [78323.256179] [worker_thread+0x0/0x110] worker_thread+0x0/0x110
kernel: [78323.256187] [kthread+0x4b/0x80] kthread+0x4b/0x80
kernel: [78323.256203] [child_rip+0xa/0x12] child_rip+0xa/0x12
kernel: [78323.256256] [kthread+0x0/0x80] kthread+0x0/0x80
kernel: [78323.256264] [child_rip+0x0/0x12] child_rip+0x0/0x12
kernel: [78323.256281]
kernel: [78323.256282]
kernel: [78323.256283] Code: 48 8b 6b 20 48 89 df e8 0c 37 00 00 4c 89 e7 e8 e4 fe ff ff
kernel: [78323.256301] RIP [klist_del+0x18/0x80] klist_del+0x18/0x80
kernel: [78323.256307] RSP <ffff81007bde5e30>
kernel: [78323.256310] CR2: 0000000000000020
kernel: [78323.256332] ---[ end trace cbd935a4181aa917 ]---