Comment 0 for bug 1603230

I found what I believe is a regression on my Gateway ne570 laptop. It was running
mythbuntu 14.04 LTS and ubuntu 15.04 releases quite well. But when I installed
ubuntu 16.04 LTS, I found dmesg and kern.log were filling with messages like this:
Jul 10 17:01:10 buus-ne570 kernel: [ 57.741630] ACPI Error: Method reached maximum
reentrancy limit (255) (20150818/dsmethod-341)
Jul 10 17:01:10 buus-ne570 kernel: [ 57.803775] ACPI Error: Method reached maximum
reentrancy limit (255) (20150818/dsmethod-341)
Jul 10 17:01:10 buus-ne570 kernel: [ 57.866294] ACPI Error: Method reached maximum
reentrancy limit (255) (20150818/dsmethod-341)
Jul 10 17:01:10 buus-ne570 kernel: [ 57.928403] ACPI Error: Method reached maximum
reentrancy limit (255) (20150818/dsmethod-341)

These messages would be repeated several times a second, and then pause for several
seconds, then start again. I believe they are the cause of more sluggish behavior
than with the older *Buntu releases.

I followed the instructions here:
https://wiki.ubuntu.com/Kernel/KernelBisection
which lead me to doing "git bisect" on the linux-stable kernel. The result lead me
to this commit:

# first bad commit: [02b771b64b73226052d6e731a0987db3b47281e9] ACPI / EC: Fix an
issue caused by the serialized _Qxx evaluations

commit 02b771b64b73226052d6e731a0987db3b47281e9
Author: Lv Zheng <email address hidden>
Date: Wed Aug 12 11:12:02 2015 +0800

    ACPI / EC: Fix an issue caused by the serialized _Qxx evaluations

    It is proven that Windows evaluates _Qxx handlers in a parallel way. This
    patch follows this fact, splits _Qxx evaluations from the NOTIFY queue to
    form a separate queue, so that _Qxx evaluations can be queued up on
    different CPUs rather than being queued up on a CPU0 bound queue.
    Event handling related callbacks are also renamed and sorted in this patch.

    Link: https://bugzilla.kernel.org/show_bug.cgi?id=94411
    Reported-and-tested-by: Gabriele Mazzotta <email address hidden>
    Signed-off-by: Lv Zheng <email address hidden>
    Signed-off-by: Rafael J. Wysocki <email address hidden>

The laptop was purchased from tigerdirect. Here's link to specs:
http://www.tigerdirect.com/applications/searchtools/item-details.asp?EdpNo=8556911

The laptop appears to be a re-branded Acer Aspire E1-570:
http://www.acer.com/ac/en/SI/content/model/NX.MGUEX.001

Both have Insyde UEFI firmware. The latest version for both is v2.06 and have same
release date, 11/11/2013, according to the Acer & Gateway support web sites, although the firmware reports an Oct date.

I realize it's quite likely that the laptop's firmware is the root cause of the
problem. However, since the problem did not exist on older kernels, I hope a patch
or workaround can be identified that will allow me to make good use of this laptop.

I assume this should also be reported to bugzilla.kernel.org. It is convenient to have the ubuntu-bug command do initial data collection.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-31-generic 4.4.0-31.50
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: buus 1830 F.... pulseaudio
CurrentDesktop: Unity
Date: Thu Jul 14 18:11:02 2016
HibernationDevice: RESUME=UUID=aa093ba8-768a-4c3f-a993-de6331fe2190
InstallationDate: Installed on 2016-07-01 (12 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
MachineType: Gateway NE570
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-31-generic.efi.signed root=UUID=b3005ae3-98ce-446f-a4d9-8af24cf4c3ae ro vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-4.4.0-31-generic N/A
 linux-backports-modules-4.4.0-31-generic N/A
 linux-firmware 1.157.2
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/08/2013
dmi.bios.vendor: Insyde Corp.
dmi.bios.version: V2.06
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: EA50_CX
dmi.board.vendor: Gateway
dmi.board.version: V2.06
dmi.chassis.asset.tag: Acer Asset Tag String
dmi.chassis.type: 10
dmi.chassis.vendor: Insyde Corp.
dmi.chassis.version: V2.06
dmi.modalias: dmi:bvnInsydeCorp.:bvrV2.06:bd10/08/2013:svnGateway:pnNE570:pvrV2.06:rvnGateway:rnEA50_CX:rvrV2.06:cvnInsydeCorp.:ct10:cvrV2.06:
dmi.product.name: NE570
dmi.product.version: V2.06
dmi.sys.vendor: Gateway