Comment 7 for bug 605124

Created an attachment (id=37003)
dmesg with 2.6.34-rc4 mainline build

(In reply to comment #6)
> Looks like it fails when i915 loads:
>
> [ 11.262370] i915 0000:00:02.0: power state changed by ACPI to D0
> [ 11.262427] i915 0000:00:02.0: power state changed by ACPI to D0
> [ 11.262437] i915 0000:00:02.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16
> [ 11.262443] i915 0000:00:02.0: setting latency timer to 64
> [ 11.287021] BUG: unable to handle kernel NULL pointer dereference at (null)

If you mean that the BUG arrives right after the i915 lines, that may be a coincidence. Running with Ubuntu's mainline build of 2.6.35-rc4 I get

[ 13.106855] i915 0000:00:02.0: power state changed by ACPI to D0
[ 13.106912] i915 0000:00:02.0: power state changed by ACPI to D0
[ 13.106922] i915 0000:00:02.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16
[ 13.106928] i915 0000:00:02.0: setting latency timer to 64
[ 13.135340] e1000e 0000:00:19.0: irq 42 for MSI/MSI-X
[ 13.135722] ADDRCONF(NETDEV_UP): eth0: link is not ready
[...]
[ 14.464944] e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None
[ 14.464949] e1000e 0000:00:19.0: eth0: 10/100 speed: disabling TSO
[ 14.465228] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 14.505338] plymouthd:329 freeing invalid memtype e012c000-e0258000
[ 14.508271] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 14.508279] IP: [<c05ca358>] __mutex_lock_slowpath+0x88/0x120
[...]

The funny thing is that with 2.6.35-rc4 and -rc5 mainline builds, xorg works just fine, no messages in Xorg.0.log, etc, so I thought it was Ubuntu specific. But the same thing appears in dmesg on some boots.

Will try older mainline builds, and then git-bisect after than if necessary.