[Acer Aspire 4820TG] Kernel Oops - unable to handle kernel NULL pointer dereference at 00000004; EIP is at drm_mm_remove_node+0x51/0xf0 [drm]

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Can you see if this issue also happens with the Vivid daily image:
http://cdimage.ubuntu.com/daily-live/current/

I tested the Vidi daily image and also got some kernel Oops errors, but the stacktrace was different so I filed a new bug here:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1414789

If you need another test, I'm happy to help.

The laptop model with this issues is: Acer Aspire 4820TG

LAva, could you please test the latest upstream kernel available from the very top line at the top of the page (the release names are irrelevant for testing, and please do not test the daily folder) following https://wiki.ubuntu.com/KernelMainlineBuilds ? It will allow additional upstream developers to examine the issue.

If the test did not allow you to test to the issue (ex. you couldn't boot into the OS) please make a comment in your report about this, and continue to test the next most recent kernel version until you can test to the issue. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this bug is fixed in the mainline kernel, please add the following tags by clicking on the yellow circle with a black pencil icon, next to the word Tags, located at the bottom of the report description:
kernel-fixed-upstream
kernel-fixed-upstream-3.XY-rcZ

Where XY and Z are numbers corresponding to the kernel version.

If the mainline kernel does not fix this bug, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-3.XY-rcZ

Once testing of the upstream kernel is complete, please mark this bug's Status as Confirmed. Please let us know your results.

Thank you for your understanding.

I tested the upstream kernel on my current Ubuntu 14.04 installation, but still get the same issues.
linux-image-3.19.0-031900rc6

The following packages were used:
linux-image-3.19.0-031900rc6-generic_3.19.0-031900rc6.201501261152_amd64.deb
linux-headers-3.19.0-031900rc6_3.19.0-031900rc6.201501261152_all.deb
linux-headers-3.19.0-031900rc6-generic_3.19.0-031900rc6.201501261152_amd64.deb

from this location: http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.19-rc6-vivid/

I also installed a new linux-firmware package, because otherwise the kernel installation would log some warnings about missing firmeware files for the radeon module.

I used the package from 14.10: http://packages.ubuntu.com/utopic/linux-firmware
linux-firmware_1.138_all.deb

This is the first stack trace I get:

[ 20.620150] WARNING: CPU: 2 PID: 154 at /home/kernel/COD/linux/drivers/gpu/drm/radeon/radeon_gart.c:234 radeon_gart_unbind+0xda/0xf0 [radeon]()
[ 20.620151] trying to unbind memory from uninitialized GART !
[ 20.620152] Modules linked in: ctr ccm arc4 brcmsmac rfcomm bnep cordic bluetooth brcmutil b43 mac80211 intel_powerclamp coretemp kvm_intel cfg80211 ssb kvm snd_seq_midi binfmt_misc uvcvideo snd_hda_codec_realtek snd_seq_midi_event snd_hda_codec_generic crct10dif_pclmul snd_hda_codec_hdmi snd_rawmidi videobuf2_vmalloc videobuf2_memops crc32_pclmul videobuf2_core ghash_clmulni_intel v4l2_common videodev acer_wmi sparse_keymap snd_hda_intel snd_hda_controller aesni_intel snd_hda_codec snd_hwdep media aes_x86_64 lrw snd_pcm gf128mul glue_helper joydev ablk_helper cryptd snd_seq snd_seq_device snd_timer serio_raw intel_ips snd mei_me bcma soundcore parport_pc mei lpc_ich ppdev mac_hid lp parport amdkfd amd_iommu_v2 radeon i915 psmouse ttm i2c_algo_bit ahci drm_kms_helper libahci drm atl1c wmi video
[ 20.620185] CPU: 2 PID: 154 Comm: kworker/u16:5 Not tainted 3.19.0-031900rc6-generic #201501261152
[ 20.620186] Hardware name: Acer /JM41_CP, BIOS V1.25 03/16/2011
[ 20.620193] Workqueue: kacpi_hotplug acpi_hotplug_work_fn
[ 20.620194] 00000000000000ea ffff8801312af6f8 ffffffff817c4584 0000000000000007
[ 20.620196] ffff8801312af748 ffff8801312af738 ffffffff81076df7 ffffffff8141e130
[ 20.620198] ffff880036098000 ffff8801312af948 ffff880036098728 ffff8800ad234f00
[ 20.620200] Call Trace:
[ 20.620206] [<ffffffff817c4584>] dump_stack+0x45/0x57
[ 20.620211] [<ffffffff81076df7>] warn_slowpath_common+0x97/0xe0
[ 20.620215] [<ffffffff8141e130>] ? update_attr.isra.2+0xa0/0xa0
[ 20.620217] [<ffffffff81076ef6>] warn_slowpath_fmt+0x46/0x50
[ 20.620225] [<ffffffff814aa454>] ? vt_console_print+0x2d4/0x3b0
[ 20.620235] [<ffffffffc065053a>] radeon_gart_unbind+0xda/0xf0 [radeon]
[ 20.620245] [<ffffffffc064cbf2>] radeon_ttm_backend_unbind+0x22/0x40 [radeon]
[ 20.620250] [<ffffffffc0495177>] ttm_tt_unbind+0x27/0x40 [ttm]
[ 20.620255] [<ffffffffc0499b68>] ttm_bo_move_ttm+0xf8/0x130 [ttm]
[ 20.620259] [<ffffffffc0497326>] ttm_bo_handle_move_mem+0x636/0x6f0 [ttm]
[ 20.620262] [<ffffffff810cc888>] ? console_unlock+0x18/0x30
[ 20.620263] [<ffffffff810cd1ae>] ? vprintk_emit+0x25e/0x510
[ 20.620266] [<ffffffff810ddb5c>] ? internal_add_...

This is the whole dmesg file for the upstream kernel test (3.19.0-031900rc6)

LAva, if you switched to using fglrx as outlined in https://help.ubuntu.com/community/BinaryDriverHowto/AMD does this provide a WORKAROUND?

The fglrx driver didn't work. The X-server only started to the low graphics error message and stopped.
I tried the Additional Driver method and the manual command line method to install the driver.

But the kernel Oops did stop. I got no NULL pointer messages with the (not working) fglrx driver.

LAva, the issue you are reporting is an upstream one. Could you please report this problem upstream following the instructions verbatim at https://wiki.ubuntu.com/Bugs/Upstream/kernel , and create a report at https://bugs.freedesktop.org/enter_bug.cgi?product=xorg&component=Driver/Radeon ?

Please provide a direct URL once you have made it so that it may be tracked.

Thank you for your understanding.

I reported the bug here:
https://bugs.freedesktop.org/show_bug.cgi?id=88927