Kernel Oops - unable to handle kernel NULL pointer dereference at 0000000000000010; EIP is at fb_release+0x26/0x60

[LAva]

My laptop has a kernel problem with the Ubuntu 15.04 live disk.

The Kernel reports constantly about a NULL pointer reference.

Sometimes the X-server starts without the Unity interface and the UI freezes constantly for a few seconds.
It often ends with a complete freeze of the computer.

Other times the computer freezes before the desktop was loaded.

I think it could be the radeon driver for my ATI Mobility Radeon HD 5650.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: linux-image-3.18.0-9-generic 3.18.0-9.10
ProcVersionSignature: Ubuntu 3.18.0-9.10-generic 3.18.2
Uname: Linux 3.18.0-9-generic x86_64
ApportVersion: 2.15.1-0ubuntu2
Architecture: amd64
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D1p', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/controlC0', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CasperVersion: 1.349
Date: Mon Jan 26 21:52:58 2015
LiveMediaBuild: Ubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20150126)
ProcEnviron:
 TERM=linux
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: noprompt cdrom-detect/try-usb=true persistent file=/cdrom/preseed/username.seed boot=casper initrd=/casper/initrd.lz quiet splash -- BOOT_IMAGE=/casper/vmlinuz.efi
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
 linux-restricted-modules-3.18.0-9-generic N/A
 linux-backports-modules-3.18.0-9-generic N/A
 linux-firmware 1.141
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/16/2011
dmi.bios.vendor: INSYDE
dmi.bios.version: V1.25
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: JM41_CP
dmi.board.vendor: Acer
dmi.board.version: Base Board Version
dmi.chassis.type: 10
dmi.chassis.vendor: Chassis Manufacturer
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnINSYDE:bvrV1.25:bd03/16/2011:svnAcer:pn:pvrV1.25:rvnAcer:rnJM41_CP:rvrBaseBoardVersion:cvnChassisManufacturer:ct10:cvrChassisVersion:
dmi.product.version: V1.25
dmi.sys.vendor: Acer

[Brad Figg (brad-figg)]

This change was made by a bot.

[LAva (lavalanche)]

Additional Information: the laptop model with this issues is "Acer Aspire 4820TG"

[Brad Figg (brad-figg)]

Thank you for taking the time to file a bug report on this issue.

However, given the number of bugs that the Kernel Team receives during any development cycle it is impossible for us to review them all. Therefore, we occasionally resort to using automated bots to request further testing. This is such a request.

We have noted that there is a newer version of the development kernel than the one you last tested when this issue was found. Please test again with the newer kernel and indicate in the bug if this issue still exists or not.

You can update to the latest development kernel by simply running the following commands in a terminal window:

    sudo apt-get update
    sudo apt-get dist-upgrade

If the bug still exists, change the bug status from Incomplete to Confirmed. If the bug no longer exists, change the bug status from Incomplete to Fix Released.

If you want this bot to quit automatically requesting kernel tests, add a tag named: bot-stop-nagging.

 Thank you for your help, we really do appreciate it.

[LAva (lavalanche)]

I think I fixed the problem by improving the slot_no_hotplug function in /drivers/pci/hotplug/acpiphp_glue.c

As far as I can tell the radeon driver set the ignore_hotplug on my radeon pci device, but the slot_no_hotplug function never got deep enough to reach the pci device with this flag.

After I added the functionality to iterate through all the subordinate pci devices, the function got to the flag and didn't remove my radeon device after it was powered down by the radeon driver (which is the expected behaviour).

[LAva (lavalanche)]

I think I fixed the problem by improving the slot_no_hotplug function in /drivers/pci/hotplug/acpiphp_glue.c

As far as I can tell the radeon driver set the ignore_hotplug on my radeon pci device, but the slot_no_hotplug function never got deep enough to reach the pci device with this flag.

After I added the functionality to iterate through all the subordinate pci devices, the function got to the flag and didn't remove my radeon device after it was powered down by the radeon driver (which is the expected behaviour).

[Joseph Salisbury (jsalisbury)]

Thank you for providing a patch, and making Ubuntu better.

Can you provide some information on the status of the patch with regards to getting it merged upstream? Has it been sent upstream, what sort of feedback has it received, is it getting applied to a subsystem maintainer's tree, etc?

People affected by this bug are probably wondering why the kernel team doesn't just apply the patch and fix it. The reason is that the kernel team is reluctant (not opposed) to apply any patch to a stable kernel that is not from upstream. Applying patches that don't come from upstream add greatly to the support of the kernel as other upstream patches may touch the same area as the non-upstream patch and may prevent them from applying cleanly.

To submit your patch, send your patch with the detailed description/changelog and your Signoff (ending with Signed-off-by: your name <email>), to the emails listed from ./scripts/get_maintainer.pl drivers/SUBSYSTEM-DETAILS (the get_maintainer.pl is from the kernel sources). Once you have sent the patch upstream and it's accepted, please drop a note here so that we can cherry-pick/include the patch into Ubuntu kernel.