Comment 2 for bug 761723

This also impacts me. Here's the relevant part of dmesg:

Apr 26 16:24:38 jm-t500 avahi-dnsconfd[1147]: Successfully connected to Avahi daemon.
Apr 26 16:24:39 jm-t500 kernel: [ 18.789976] BUG: unable to handle kernel NULL pointer dereference at 0000008e
Apr 26 16:24:39 jm-t500 kernel: [ 18.790015] IP: [<f85cf7be>] drm_mode_connector_update_edid_property+0x5e/0x170 [drm]
Apr 26 16:24:39 jm-t500 kernel: [ 18.790065] *pdpt = 0000000030d60001 *pde = 0000000000000000
Apr 26 16:24:39 jm-t500 kernel: [ 18.790092] Oops: 0000 [#1] SMP
Apr 26 16:24:39 jm-t500 kernel: [ 18.790111] last sysfs file: /sys/module/bluetooth/initstate
Apr 26 16:24:39 jm-t500 kernel: [ 18.790140] Modules linked in: bnep snd_hda_codec_conexant l2cap snd_hda_intel snd_hda_codec snd_hwdep snd_pcm thinkpad_acpi snd_seq_midi snd_rawmidi arc4 snd_seq_midi_event snd_seq snd_timer joydev pcmcia yenta_socket r852 sm_common nand nand_ids snd_seq_device iwlagn pcmcia_rsrc radeon(+) snd lp btusb iwlcore ttm mac80211 nand_ecc mtd psmouse uvcvideo videodev hid_apple pcmcia_core soundcore cfg80211 tpm_tis tpm tpm_bios nvram serio_raw usbhid hid snd_page_alloc bluetooth parport i915 firewire_ohci firewire_core sdhci_pci drm_kms_helper drm ahci sdhci crc_itu_t e1000e libahci i2c_algo_bit video
Apr 26 16:24:39 jm-t500 kernel: [ 18.790457]
Apr 26 16:24:39 jm-t500 kernel: [ 18.790467] Pid: 551, comm: modprobe Not tainted 2.6.38-8-generic-pae #42-Ubuntu LENOVO 20553AU/20553AU
Apr 26 16:24:39 jm-t500 kernel: [ 18.790517] EIP: 0060:[<f85cf7be>] EFLAGS: 00010202 CPU: 0
Apr 26 16:24:39 jm-t500 kernel: [ 18.790553] EIP is at drm_mode_connector_update_edid_property+0x5e/0x170 [drm]
Apr 26 16:24:39 jm-t500 kernel: [ 18.790589] EAX: 00000010 EBX: f604c000 ECX: f0c78000 EDX: 000080d0
Apr 26 16:24:39 jm-t500 kernel: [ 18.790616] ESI: 00000000 EDI: 00000010 EBP: f0cc5c94 ESP: f0cc5c7c
Apr 26 16:24:39 jm-t500 kernel: [ 18.790643] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
Apr 26 16:24:39 jm-t500 kernel: [ 18.790668] Process modprobe (pid: 551, ti=f0cc4000 task=f0c4e500 task.ti=f0cc4000)
Apr 26 16:24:39 jm-t500 kernel: [ 18.790700] Stack:
Apr 26 16:24:39 jm-t500 kernel: [ 18.790712] f0911000 f0c78000 00000010 f604c000 f0911000 f604c170 f0cc5ca4 f996ba9d
Apr 26 16:24:39 jm-t500 kernel: [ 18.790754] f604c000 00002000 f0cc5cd8 f99652f4 f0cc5cc8 f9964e8b 00000001 f0c18c00
Apr 26 16:24:39 jm-t500 kernel: [ 18.790797] 00000001 f604c000 f604c170 f604c000 f604c000 00002000 f604c170 f0cc5d14
Apr 26 16:24:39 jm-t500 kernel: [ 18.790839] Call Trace:
Apr 26 16:24:39 jm-t500 kernel: [ 18.790876] [<f996ba9d>] radeon_ddc_get_modes+0x4d/0xf0 [radeon]
Apr 26 16:24:39 jm-t500 kernel: [ 18.790920] [<f99652f4>] radeon_lvds_get_modes+0x24/0x280 [radeon]
Apr 26 16:24:39 jm-t500 kernel: [ 18.790964] [<f9964e8b>] ? radeon_connector_update_scratch_regs+0x6b/0x90 [radeon]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791005] [<f8584cd6>] drm_helper_probe_single_connector_modes+0xc6/0x340 [drm_kms_helper]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791051] [<f85842f3>] drm_fb_helper_initial_config+0xb3/0xf0 [drm_kms_helper]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791101] [<f9972f58>] radeon_fbdev_init+0x98/0x110 [radeon]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791146] [<f996c949>] radeon_modeset_init+0x1f9/0x220 [radeon]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791193] [<f9947e9e>] radeon_driver_load_kms+0xee/0x160 [radeon]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791236] [<f85cb884>] drm_get_pci_dev+0x144/0x2b0 [drm]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791268] [<c1035908>] ? default_spin_lock_flags+0x8/0x10
Apr 26 16:24:39 jm-t500 kernel: [ 18.791311] [<f99d55cb>] ? radeon_pci_probe+0x2f/0xc7 [radeon]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791353] [<f99d55cb>] ? radeon_pci_probe+0x2f/0xc7 [radeon]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791395] [<f99d565c>] radeon_pci_probe+0xc0/0xc7 [radeon]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791423] [<c129efe7>] local_pci_probe+0x47/0xb0
Apr 26 16:24:39 jm-t500 kernel: [ 18.791447] [<c12a0468>] pci_device_probe+0x68/0x90
Apr 26 16:24:39 jm-t500 kernel: [ 18.791474] [<c134d43d>] really_probe+0x4d/0x150
Apr 26 16:24:39 jm-t500 kernel: [ 18.791497] [<c135562b>] ? pm_runtime_barrier+0x4b/0xb0
Apr 26 16:24:39 jm-t500 kernel: [ 18.791525] [<c134d6dc>] driver_probe_device+0x3c/0x60
Apr 26 16:24:39 jm-t500 kernel: [ 18.791549] [<c134d781>] __driver_attach+0x81/0x90
Apr 26 16:24:39 jm-t500 kernel: [ 18.791571] [<c134d700>] ? __driver_attach+0x0/0x90
Apr 26 16:24:39 jm-t500 kernel: [ 18.791598] [<c134c838>] bus_for_each_dev+0x48/0x70
Apr 26 16:24:39 jm-t500 kernel: [ 18.791624] [<c129fe70>] ? pci_device_remove+0x0/0xf0
Apr 26 16:24:39 jm-t500 kernel: [ 18.791649] [<c134d2ee>] driver_attach+0x1e/0x20
Apr 26 16:24:39 jm-t500 kernel: [ 18.791670] [<c134d700>] ? __driver_attach+0x0/0x90
Apr 26 16:24:39 jm-t500 kernel: [ 18.791696] [<c134cf08>] bus_add_driver+0xb8/0x250
Apr 26 16:24:39 jm-t500 kernel: [ 18.791720] [<c129fe70>] ? pci_device_remove+0x0/0xf0
Apr 26 16:24:39 jm-t500 kernel: [ 18.791746] [<c134d9c6>] driver_register+0x66/0x110
Apr 26 16:24:39 jm-t500 kernel: [ 18.791772] [<c129f585>] __pci_register_driver+0x45/0xb0
Apr 26 16:24:39 jm-t500 kernel: [ 18.791806] [<f85cbcd6>] drm_pci_init+0x96/0xc0 [drm]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791841] [<f85c4124>] drm_init+0x54/0x70 [drm]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791882] [<f9a110b7>] radeon_init+0xb7/0x1000 [radeon]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791913] [<c1003165>] do_one_initcall+0x35/0x170
Apr 26 16:24:39 jm-t500 kernel: [ 18.791949] [<f9a11000>] ? radeon_init+0x0/0x1000 [radeon]
Apr 26 16:24:39 jm-t500 kernel: [ 18.791977] [<c10922db>] sys_init_module+0xdb/0x230
Apr 26 16:24:39 jm-t500 kernel: [ 18.792003] [<c100ab5f>] sysenter_do_call+0x12/0x28
Apr 26 16:24:39 jm-t500 kernel: [ 18.792004] Code: 10 89 f0 c7 46 08 00 01 10 00 c7 46 0c 00 02 20 00 e8 c7 63 b5 c8 8b 7d f0 85 ff 0f 84 c4 00 00 00 8b 45 f0 ba d0 80 00 00 8b 0b <0f> b6 78 7e 89 4d e8 83 c7 01 c1 e7 07 8d 47 18 e8 6d 6a b5 c8
Apr 26 16:24:39 jm-t500 kernel: [ 18.792004] EIP: [<f85cf7be>] drm_mode_connector_update_edid_property+0x5e/0x170 [drm] SS:ESP 0068:f0cc5c7c
Apr 26 16:24:39 jm-t500 kernel: [ 18.792004] CR2: 000000000000008e
Apr 26 16:24:39 jm-t500 udevd-work[487]: '/sbin/modprobe -bv pci:v00001002d00009591sv000017AAsd00002116bc03sc00i00' unexpected exit with status 0x0009
Apr 26 16:24:39 jm-t500 kernel: [ 18.813581] ---[ end trace 256f52b10f0172f2 ]---

This is a Thinkpad t500 with a Radeon HD 3650

uname -a: Linux jm-t500 2.6.38-8-generic-pae #42-Ubuntu SMP Mon Apr 11 05:17:09 UTC 2011 i686 i686 i386 GNU/Linux

lspci -vnn | grep VGA:

00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07) (prog-if 00 [VGA controller])
01:00.0 VGA compatible controller [0300]: ATI Technologies Inc Mobility Radeon HD 3650 [1002:9591] (prog-if 00 [VGA controller])