I have radeon xpress 200M, and drm (linux-drm-20090320-kernelsource.tar.bz2) causes kernel pani in the following cases:
1. On hibernating (tux-on-ice) [frequently]
2. On power off [always]

Here is my messages for the 1st case:
Jun  3 07:21:16 logos BUG: unable to handle kernel NULL pointer dereference at 0000012c
Jun  3 07:21:16 logos IP: [<c02073af>] vsnprintf+0xb0/0x8b4
Jun  3 07:21:16 logos *pde = 364c0067 *pte = 00000000 
Jun  3 07:21:16 logos Oops: 0002 [#1] 
Jun  3 07:21:16 logos last sysfs file: /sys/devices/pci0000:00/0000:00:13.2/usb3/3-0:1.0/bInterfaceP
rotocol
Jun  3 07:21:16 logos Modules linked in: uhci_hcd ehci_hcd ohci_hcd usb_storage radeon drm hidp bnep
 rfcomm l2cap snd_pcm_oss snd_mixer_oss bluetooth snd_seq_oss snd_seq_midi_event snd_seq snd_seq_dev
ice fuse snd_atiixp snd_atiixp_modem snd_ac97_codec ac97_bus snd_pcm snd_timer tg3 snd soundcore lib
phy usbcore psmouse video snd_page_alloc [last unloaded: ohci_hcd]
Jun  3 07:21:16 logos 
Jun  3 07:21:16 logos Pid: 4618, comm: X Not tainted (2.6.29-tuxonice-r2 #1) 18436NG
Jun  3 07:21:16 logos EIP: 0060:[<c02073af>] EFLAGS: 00213287 CPU: 0
Jun  3 07:21:16 logos EIP is at vsnprintf+0xb0/0x8b4
Jun  3 07:21:16 logos EAX: 0000118b EBX: 00000000 ECX: 0000012c EDX: 0000112c
Jun  3 07:21:16 logos ESI: f642fce4 EDI: f642fcb4 EBP: f642fcc4 ESP: f642fba4
Jun  3 07:21:16 logos DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
Jun  3 07:21:16 logos Process X (pid: 4618, ti=f642e000 task=f706c660 task.ti=f642e000)
Jun  3 07:21:16 logos Stack:
Jun  3 07:21:16 logos f642fcb4 00000000 f8690c89 00001000 0000012c f642fcec 0000012c 0000112c
Jun  3 07:21:16 logos 00000018 f1a97018 004d08fa 00000001 0020dd5d f733bc00 00000000 0000000c
Jun  3 07:21:16 logos 0000000c 0000000c 00000010 00000010 00000180 00000560 f7142518 f7142500
Jun  3 07:21:16 logos Call Trace:
Jun  3 07:21:16 logos [<f8690c89>] ? radeon_set_pcigart+0x271/0x6e6 [radeon]
Jun  3 07:21:16 logos [<c0198dfd>] ? inode2sd+0x142/0x155
Jun  3 07:21:16 logos [<c01a5e2a>] ? pathrelse+0x1b/0x2f
Jun  3 07:21:16 logos [<c019988c>] ? reiserfs_update_sd_size+0x278/0x280
Jun  3 07:21:16 logos [<c0198dfd>] ? inode2sd+0x142/0x155
Jun  3 07:21:16 logos [<c0326ed9>] ? mutex_lock+0xe/0x1d
Jun  3 07:21:16 logos [<c01a5e2a>] ? pathrelse+0x1b/0x2f
Jun  3 07:21:16 logos [<c01ab7f8>] ? do_journal_end+0x2b5/0xb6d
Jun  3 07:21:16 logos [<c019988c>] ? reiserfs_update_sd_size+0x278/0x280
Jun  3 07:21:16 logos [<c0207c19>] ? snprintf+0x15/0x17
Jun  3 07:21:16 logos [<f868f0c8>] ? dri_library_name+0x3f/0x43 [radeon]
Jun  3 07:21:16 logos [<f8690c89>] ? radeon_set_pcigart+0x271/0x6e6 [radeon]
Jun  3 07:21:16 logos [<f8691156>] ? radeon_cp_resume+0x58/0xa5 [radeon]
Jun  3 07:21:16 logos [<f86910fe>] ? radeon_cp_resume+0x0/0xa5 [radeon]
Jun  3 07:21:16 logos [<f864e165>] ? drm_unlocked_ioctl+0x1a3/0x21a [drm]
Jun  3 07:21:16 logos [<c01ac200>] ? journal_end+0x99/0xa2
Jun  3 07:21:16 logos [<c0199a45>] ? reiserfs_write_end+0x1b1/0x1df
Jun  3 07:21:16 logos [<c0143780>] ? generic_file_buffered_write+0x113/0x233
Jun  3 07:21:16 logos [<c01437d5>] ? generic_file_buffered_write+0x168/0x233
Jun  3 07:21:16 logos [<c0143e1b>] ? __generic_file_aio_write_nolock+0x3e3/0x41a
Jun  3 07:21:16 logos [<c01519df>] ? handle_mm_fault+0x1dc/0x40e
Jun  3 07:21:16 logos [<c01445f8>] ? generic_file_aio_write+0x62/0xb4
Jun  3 07:21:16 logos [<c015e7de>] ? do_sync_write+0xaa/0xe8
Jun  3 07:21:16 logos [<c012336d>] ? autoremove_wake_function+0x0/0x33
Jun  3 07:21:16 logos [<f864e1dc>] ? drm_ioctl+0x0/0x11 [drm]
Jun  3 07:21:16 logos [<f864e1eb>] ? drm_ioctl+0xf/0x11 [drm]
Jun  3 07:21:16 logos [<c0167e46>] ? vfs_ioctl+0x3e/0x51
Jun  3 07:21:16 logos [<c0168564>] ? do_vfs_ioctl+0x420/0x461
Jun  3 07:21:16 logos [<c015f012>] ? vfs_write+0xf0/0x104
Jun  3 07:21:16 logos [<c01685d1>] ? sys_ioctl+0x2c/0x45
Jun  3 07:21:16 logos [<c0102c45>] ? sysenter_do_call+0x12/0x25
Jun  3 07:21:16 logos [<c0320000>] ? wext_handle_ioctl+0x13b/0x178
Jun  3 07:21:16 logos Code: 89 bd e0 fe ff ff 89 8d f8 fe ff ff e9 ce 07 00 00 31 db 3c 25 74 21 8b 95 fc fe ff ff 39 95 f8 fe ff ff 73 08 8b 8d f8 fe ff ff <88> 01 ff 85 f8 fe ff ff e9 a1 07 00 00 ff 85 e8 fe ff ff 8b bd 
Jun  3 07:21:16 logos EIP: [<c02073af>] vsnprintf+0xb0/0x8b4 SS:ESP 0068:f642fba4
Jun  3 07:21:16 logos ---[ end trace 2ead4e5f87a1bffd ]---
Jun  3 07:21:16 logos [drm:drm_release] *ERROR* Device busy: 1 0

Here is another stacktrace for 1st case:
May 19 14:09:34 logos BUG: unable to handle kernel paging request at fffffffe
May 19 14:09:34 logos IP: [<f856bd68>] radeon_set_pcigart+0x298/0x6e6 [radeon]
May 19 14:09:34 logos *pde = 00459067 *pte = 00000000 
May 19 14:09:34 logos Oops: 0002 [#1] 
May 19 14:09:34 logos last sysfs file: /sys/class/power_supply/AC/online
May 19 14:09:34 logos Modules linked in: uhci_hcd ehci_hcd ohci_hcd usb_storage btusb bnep hidp snd_
pcm_oss rfcomm snd_mixer_oss snd_seq_oss l2cap snd_seq_midi_event snd_seq snd_seq_device bluetooth f
use radeon drm snd_atiixp_modem snd_atiixp snd_ac97_codec ac97_bus snd_pcm snd_timer snd soundcore u
sbcore snd_page_alloc tg3 psmouse video libphy [last unloaded: ohci_hcd]
May 19 14:09:34 logos 
May 19 14:09:34 logos Pid: 4670, comm: X Not tainted (2.6.29-tuxonice-r1 #2) 18436NG
May 19 14:09:34 logos EIP: 0060:[<f856bd68>] EFLAGS: 00213246 CPU: 0
May 19 14:09:34 logos EIP is at radeon_set_pcigart+0x298/0x6e6 [radeon]
May 19 14:09:34 logos EAX: fffffffe EBX: f73f0c00 ECX: f73f0c00 EDX: 000000ff
May 19 14:09:34 logos ESI: 00000001 EDI: f44b66c0 EBP: f6b95ef0 ESP: f6b95ee8
May 19 14:09:34 logos DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
May 19 14:09:34 logos Process X (pid: 4670, ti=f6b94000 task=f70ffc40 task.ti=f6b94000)
May 19 14:09:34 logos Stack:
May 19 14:09:34 logos f73f0c00 f73ed400 f6b95f04 f856c211 f85854d8 00000000 00006458 f6b95f24
May 19 14:09:34 logos f85173f8 f44b66c0 f73ed400 f856c1b6 f6bca540 f851724c 00000000 f6b95f38
May 19 14:09:34 logos c01690c2 00000000 f6bca540 f68906a0 f6b95f98 c01697e0 0000000a 00000000
May 19 14:09:34 logos Call Trace:
May 19 14:09:34 logos [<f856c211>] ? radeon_cp_resume+0x5b/0xab [radeon]
May 19 14:09:34 logos [<f85173f8>] ? drm_ioctl+0x1ac/0x223 [drm]
May 19 14:09:34 logos [<f856c1b6>] ? radeon_cp_resume+0x0/0xab [radeon]
May 19 14:09:34 logos [<f851724c>] ? drm_ioctl+0x0/0x223 [drm]
May 19 14:09:34 logos [<c01690c2>] ? vfs_ioctl+0x3e/0x51
May 19 14:09:34 logos [<c01697e0>] ? do_vfs_ioctl+0x420/0x461
May 19 14:09:34 logos [<c016029e>] ? vfs_write+0xf0/0x104
May 19 14:09:34 logos [<c016984d>] ? sys_ioctl+0x2c/0x45
May 19 14:09:34 logos [<c0102c85>] ? sysenter_do_call+0x12/0x25
May 19 14:09:34 logos Code: 10 05 68 01 00 00 89 10 ba 39 00 00 00 89 d8 e8 6b e3 ff ff 8b 83 1c 03 00 00 25 ff ff 00 00 83 e8 12 83 01 00 00 89 10 ba 39 00 <00> 00 89 d8 e8 6b e3 ff 01 00 00 89 10 ba 39 00 00 00 89 d8 e8 
May 19 14:09:34 logos EIP: [<f856bd68>] radeon_set_pcigart+0x298/0x6e6 [radeon] SS:ESP 0068:f6b95ee8
May 19 14:09:34 logos ---[ end trace b0d184eab1212cba ]---
May 19 14:09:34 logos [drm:drm_release] *ERROR* Device busy: 1