[15.10 Regression] LightDM unity-greeter login sound has noisy distortion after 15.10 Wily upgrade

[Sb]

Hi, I just upgraded from Ubuntu 15.04 to 15.10 beta. Now when the LightDM unity-greeter screen appears, it produces a loud distortion noise where the Ubuntu drums should sound. It was working fine in 15.04 and all prior versions. Apart from this sound works fine after logging into Ubuntu.
---
ApportVersion: 2.18.1-0ubuntu1
Architecture: i386
CurrentDesktop: Unity
DistroRelease: Ubuntu 15.10
InstallationDate: Installed on 2015-07-26 (56 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release i386 (20150422)
Package: unity-greeter 15.10.1-0ubuntu1
PackageArchitecture: i386
ProcVersionSignature: Ubuntu 4.2.0-10.12-generic 4.2.0
Tags: wily
Uname: Linux 4.2.0-10-generic i686
UpgradeStatus: Upgraded to wily on 2015-09-20 (1 days ago)
UserGroups: adm lpadmin sambashare sudo
_MarkForUpload: True
---
ApportVersion: 2.18.1-0ubuntu1
Architecture: i386
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: miriam 1808 F.... pulseaudio
 /dev/snd/controlC1: miriam 1808 F.... pulseaudio
CurrentDesktop: Unity
DistroRelease: Ubuntu 15.10
HibernationDevice: RESUME=UUID=cc55c385-01f9-45f4-b217-66627c7455be
InstallationDate: Installed on 2015-07-26 (56 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release i386 (20150422)
MachineType: LENOVO 20AR006RUS
Package: unity-greeter 15.10.1-0ubuntu1
PackageArchitecture: i386
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-10-generic root=UUID=6e3af67c-126e-4f64-8004-8e87ef62201c ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 4.2.0-10.12-generic 4.2.0
RelatedPackageVersions:
 linux-restricted-modules-4.2.0-10-generic N/A
 linux-backports-modules-4.2.0-10-generic N/A
 linux-firmware 1.148
Tags: wily wily
UdevLog: Error: [Errno 2] No existe el archivo o el directorio: '/var/log/udev'
Uname: Linux 4.2.0-10-generic i686
UpgradeStatus: Upgraded to wily on 2015-09-20 (1 days ago)
UserGroups: adm lpadmin sambashare sudo
_MarkForUpload: True
dmi.bios.date: 06/22/2015
dmi.bios.vendor: LENOVO
dmi.bios.version: GJET84WW (2.34 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20AR006RUS
dmi.board.vendor: LENOVO
dmi.board.version: SDK0E50510 PRO
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvrGJET84WW(2.34):bd06/22/2015:svnLENOVO:pn20AR006RUS:pvrThinkPadT440s:rvnLENOVO:rn20AR006RUS:rvrSDK0E50510PRO:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 20AR006RUS
dmi.product.version: ThinkPad T440s
dmi.sys.vendor: LENOVO

[Sb (sb56637)]

Appears to be a kernel problem. When I boot the new 15.10 system with the Vivid 3.19 kernel this bug doesn't exist.

[Sb (sb56637)]

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[Brad Figg (brad-figg)]

This change was made by a bot.

[penalvch (penalvch)]

Sb, thank you for reporting this and helping make Ubuntu better. To clarify, if you boot into a previous kernel from Vivid, is this issue still reproducible?

[Sb (sb56637)]

Thanks Christopher for the reply. When I boot with the 3.19 kernel from Vivid, this issue is *not* reproducible.

[penalvch (penalvch)]

Sb, the next step is to fully commit bisect from kernel 3.19 to 4.2 in order to identify the last good kernel commit, followed immediately by the first bad one. This will allow for a more expedited analysis of the root cause of your issue. Could you please do this following https://wiki.ubuntu.com/Kernel/KernelBisection ?

Please note, finding adjacent kernel versions is not fully commit bisecting.

Thank you for your understanding.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs

[Sb (sb56637)]

Unfortunately I am not capable of doing the bisection, my apologies. However, this is extremely common hardware (Thinkpad T440s with all-Intel everything) that is normally extremely Linux compatible. So it would be worth the trouble to fix this very annoying bug, in my opinion.

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]

[penalvch (penalvch)]

Sb, to advise, the bisection article was written for both a technical, and non-technical audience. Hence, could you please advise which step in the article you are on?