kernel 2.6.22-12 BUG message from dmesg in 7.10 beta

I am trying the ubuntu 7.10 beta desktop i386 live CD and
I found an explicit BUG message from kernel when issuing the 'dmesg' command. I report the part which appears after the
------------------------[ CUT HERE ]---------------------------- message:

[ 1646.408000] ------------[ cut here ]------------
[ 1646.408000] kernel BUG at /build/buildd/linux-ubuntu-modules-2.6.22-2.6.22/debian/build/build-generic/fs/unionfs/inode.c:1057!
[ 1646.408000] invalid opcode: 0000 [#1]
[ 1646.408000] SMP
[ 1646.408000] Modules linked in: ipv6 af_packet rfcomm l2cap bluetooth ppdev lp powernow_k7 cpufreq_userspace cpufreq_stats cpufreq_powersave cpufreq_ondemand freq_table cpufreq_conservative video sbs container button dock battery asus_acpi ac joydev pcmcia snd_intel8x0 snd_ac97_codec ac97_bus snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy irtty_sir sir_dev yenta_socket rsrc_nonstatic pcspkr psmouse wbsd mmc_core parport_pc parport snd_seq_oss snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq snd_timer snd_seq_device snd irda crc_ccitt pcmcia_core serio_raw soundcore snd_page_alloc i2c_sis96x shpchp i2c_core pci_hotplug sis_agp evdev radeon drm agpgart squashfs loop unionfs nls_cp437 isofs usbhid hid ext3 jbd mbcache sg sr_mod cdrom sd_mod ohci1394 ieee1394 ehci_hcd sis900 mii ohci_hcd usbcore pata_sis ata_generic libata scsi_mod thermal processor fan fuse apparmor commoncap
[ 1646.408000] CPU: 0
[ 1646.408000] EIP: 0060:[<f897803c>] Not tainted VLI
[ 1646.408000] EFLAGS: 00210246 (2.6.22-12-generic #1)
[ 1646.408000] EIP is at unionfs_setattr+0x4ac/0x4c0 [unionfs]
[ 1646.408000] eax: f6bc39e0 ebx: 00000000 ecx: 00000000 edx: 00000000
[ 1646.408000] esi: e1ed6ab0 edi: 00000000 ebp: 00000000 esp: e3789dcc
[ 1646.408000] ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068
[ 1646.408000] Process python (pid: 22270, ti=e3788000 task=e3d1c000 task.ti=e3788000)
[ 1646.408000] Stack: f8837360 f8978110 c018819e f04964c8 c1972180 24cfc0ad 00000000 dfc6300f
[ 1646.408000] 00000300 00000000 00000000 08364134 00000001 083641f8 00000003 0000001d
[ 1646.408000] e1ed6ab0 e3789e74 ef5ec5d8 ffffff8c cd32e550 e3789e74 022111af 00000001
[ 1646.408000] Call Trace:
[ 1646.408000] [<f8978110>] unionfs_permission+0x0/0x370 [unionfs]
[ 1646.408000] [<c018819e>] permission+0x10e/0x120
[ 1646.408000] [<c01957ef>] notify_change+0x2af/0x390
[ 1646.408000] [<c017f67e>] do_truncate+0x7e/0xb0
[ 1646.408000] [<c018819e>] permission+0x10e/0x120
[ 1646.408000] [<c0189342>] may_open+0x1e2/0x270
[ 1646.408000] [<c018b76d>] open_namei+0x6d/0x600
[ 1646.408000] [<c017ee33>] do_filp_open+0x33/0x60
[ 1646.408000] [<c017eeae>] do_sys_open+0x4e/0xf0
[ 1646.408000] [<c017ef8c>] sys_open+0x1c/0x20
[ 1646.408000] [<c01041d2>] sysenter_past_esp+0x6b/0xa9
[ 1646.408000] =======================
[ 1646.408000] Code: 58 e9 97 fe ff ff 8b 42 4c 89 41 4c 8b 44 24 24 89 41 48 e9 ae fe ff ff 0f 0b eb fe 8d 76 00 0f 0b eb fe 0f 0b eb fe 0f 0b eb fe <0f> 0b eb fe 0f 0b eb fe 8d b6 00 00 00 00 8d bf 00 00 00 00 83
[ 1646.408000] EIP: [<f897803c>] unionfs_setattr+0x4ac/0x4c0 [unionfs] SS:ESP 0068:e3789dcc
[ 2318.792000] unionfs: saving rdstate with cookie 25 [1.663]
[ 2318.808000] unionfs: saving rdstate with cookie 26 [1.663]
[ 2320.196000] [drm:radeon_cp_init] *ERROR* radeon_cp_init called without lock held
[ 2320.196000] [drm:drm_unlock] *ERROR* Process 22392 using kernel context 0
[ 7983.804000] kjournald starting. Commit interval 5 seconds
[ 7983.808000] EXT3 FS on sda3, internal journal
[ 7983.808000] EXT3-fs: mounted filesystem with ordered data mode.
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Besides, while I normally run ubuntu 7.04 with beryl+radeon driver, direct rendering is disabled with this beta live CD. I do not know if it is connected in some way to the above reported error messages.

This is my hardware comfiguration:
ASUS D2500 Notebook with the following output from "lspci":

00:00.0 Host bridge: Silicon Integrated Systems [SiS] 746 Host (rev 10)
00:01.0 PCI bridge: Silicon Integrated Systems [SiS] SG86C202
00:02.0 ISA bridge: Silicon Integrated Systems [SiS] SiS963 [MuTIOL Media IO] (rev 25)
00:02.1 SMBus: Silicon Integrated Systems [SiS] SiS961/2 SMBus Controller
00:02.5 IDE interface: Silicon Integrated Systems [SiS] 5513 [IDE]
00:02.6 Modem: Silicon Integrated Systems [SiS] AC'97 Modem Controller (rev a0)
00:02.7 Multimedia audio controller: Silicon Integrated Systems [SiS] AC'97 Sound Controller (rev a0)
00:03.0 USB Controller: Silicon Integrated Systems [SiS] USB 1.0 Controller (rev 0f)
00:03.1 USB Controller: Silicon Integrated Systems [SiS] USB 1.0 Controller (rev 0f)
00:03.3 USB Controller: Silicon Integrated Systems [SiS] USB 2.0 Controller
00:04.0 Ethernet controller: Silicon Integrated Systems [SiS] SiS900 PCI Fast Ethernet (rev 90)
00:0a.0 CardBus bridge: Ricoh Co Ltd RL5c475 (rev b8)
00:0a.1 FireWire (IEEE 1394): Ricoh Co Ltd R5C551 IEEE 1394 Controller
01:00.0 VGA compatible controller: ATI Technologies Inc M9+ 5C61 [Radeon Mobility 9200 (AGP)] (rev 01)