Oops in Xorg

[Hartmut Niemann]

Hello!

My X server freezes or restarts occasionally, and this time I got something with dmesg:

[ 2275.882543] BUG: unable to handle kernel NULL pointer dereference at 00000000
[ 2275.882555] IP: [<00000000>]
[ 2275.882560] *pde = 00000000
[ 2275.882566] Oops: 0000 [#1] SMP
[ 2275.882569] Modules linked in: appletalk ax25 ipx p8023 radeon drm ipv6 vboxdrv ppdev lp nfsd auth_rpcgss exportfs nfs lockd nfs_acl sunrpc tun nls_utf8 nls_cp437 vfat fat nls_base fuse dm_snapshot dm_mirror dm_log dm_mod sbp2 loop snd_via82xx gameport snd_ac97_codec ac97_bus snd_mpu401_uart cx88_alsa snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy parport_pc parport snd_seq_oss isl6421 cx24123 snd_seq_midi snd_seq_midi_event serio_raw snd_seq psmouse snd_timer pcspkr snd_rawmidi cx88_dvb cx88_vp3054_i2c snd_seq_device videobuf_dvb dvb_core snd soundcore via_ircc snd_page_alloc irda cx8802 cx8800 cx88xx crc_ccitt ir_common i2c_viapro i2c_algo_bit tveeprom videodev v4l1_compat compat_ioctl32 v4l2_common i2c_core videobuf_dma_sg videobuf_core btcx_risc button shpchp pci_hotplug via_agp agpgart evdev ext3 jbd mbcache ide_cd_mod cdrom ide_disk ata_generic libata scsi_mod dock ide_pci_generic floppy via_rhine mii via82cxxx ide_core uhci_hcd ohci1394 ieee1394 ehci_hcd ohci_hcd usbcore thermal processor fan thermal_sys
[ 2275.882642]
[ 2275.882645] Pid: 3284, comm: Xorg Not tainted (2.6.26-1-686 #1)
[ 2275.882649] EIP: 0060:[<00000000>] EFLAGS: 00013206 CPU: 0
[ 2275.882652] EIP is at 0x0
[ 2275.882655] EAX: de512420 EBX: de512420 ECX: 00001000 EDX: 09a729c8
[ 2275.882658] ESI: 09a729c8 EDI: 00000000 EBP: 00001000 ESP: de9d1f80
[ 2275.882661]  DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
[ 2275.882664] Process Xorg (pid: 3284, ti=de9d0000 task=de24ad60 task.ti=de9d0000)
[ 2275.882667] Stack: c0174992 de9d1fa0 de511220 fffffff7 08ef93d8 de9d0000 c0174de3 de9d1fa0
[ 2275.882674]        00000000 00000000 00000000 00000020 00000000 c0103853 00000020 09a729c8
[ 2275.882680]        00001000 00000000 08ef93d8 bfc8d108 00000003 0000007b 0000007b 00000000
[ 2275.882686] Call Trace:
[ 2275.882690]  [<c0174992>] vfs_read+0x81/0x11e
[ 2275.882704]  [<c0174de3>] sys_read+0x3c/0x63
[ 2275.882713]  [<c0103853>] sysenter_past_esp+0x78/0xb1
[ 2275.882733]  =======================
[ 2275.882735] Code:  Bad EIP value.
[ 2275.882739] EIP: [<00000000>] 0x0 SS:ESP 0068:de9d1f80
[ 2275.882745] ---[ end trace 042fe1b93718ef89 ]---

The Ati drivers have been compiled from git on 2009-01-08 (because there was an 
AGP issue), the rest is "debian testing":
X.Org X Server 1.4.2
Release Date: 11 June 2008
X Protocol Version 11, Revision 0
Build Operating System: Linux Debian (xorg-server 2:1.4.2-9)
Current Operating System: Linux Ursula 2.6.26-1-686 #1 SMP Mon Dec 15 18:15:07 UTC 2008 i
686
Build Date: 15 November 2008  05:39:59PM

Device "ATI Technologies Inc RV280 [Radeon 9200 SE]

Can anybody tell me how to find out what went wrong?

With best regards
Hartmut Niemann