tcp_fastretrans_alert kernel warnings

[Lastique]

I have experienced a full system lockup, not even SysRq+REISUB could reboot the system. In the kernel logs I noticed multiple tcp_fastretrans_alert warnings and the upstream bug (https://bugzilla.kernel.org/show_bug.cgi?id=195835, https://bugzilla.kernel.org/show_bug.cgi?id=60779) seems to indicate this may be the reason.

In the attached kernel log, the hang happened immediately before the last reboot.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: linux-image-4.13.0-25-generic 4.13.0-25.29
ProcVersionSignature: Ubuntu 4.13.0-25.29-generic 4.13.13
Uname: Linux 4.13.0-25-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.7-0ubuntu3.7
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC3: lastique 3183 F.... pulseaudio
 /dev/snd/controlC1: lastique 3183 F.... pulseaudio
 /dev/snd/controlC2: lastique 3183 F.... pulseaudio
 /dev/snd/controlC0: lastique 3183 F.... pulseaudio
CurrentDesktop: KDE
Date: Fri Jan 19 22:26:36 2018
InstallationDate: Installed on 2015-05-01 (993 days ago)
InstallationMedia: Kubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
MachineType: System manufacturer System Product Name
ProcFB:

ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.13.0-25-generic root=UUID=a03f1835-52f9-4409-9da7-fe45770637ae ro quiet splash nomdmonddf nomdmonisw
RelatedPackageVersions:
 linux-restricted-modules-4.13.0-25-generic N/A
 linux-backports-modules-4.13.0-25-generic N/A
 linux-firmware 1.169.1
RfKill:
 0: hci0: Bluetooth
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
UpgradeStatus: Upgraded to artful on 2017-11-03 (76 days ago)
dmi.bios.date: 11/09/2012
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 3603
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: P8Z68-V PRO
dmi.board.vendor: ASUSTeK Computer INC.
dmi.board.version: Rev 1.xx
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr3603:bd11/09/2012:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKComputerINC.:rnP8Z68-VPRO:rvrRev1.xx:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: System Product Name
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

Did this issue start happening after an update/upgrade? Was there a prior kernel version where you were not having this particular problem?

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.15 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.15-rc9

[Lastique (andysem)]

> Did this issue start happening after an update/upgrade?

I did not have hard lockups before upgrading to 4.13.0-25. The lockup happened once, after several days past the upgrade. I did not look in the logs until after the lockup, so I can't tell if the tcp_fastretrans_alert errors were there with older kernels.

> Would it be possible for you to test the latest upstream kernel?

Given that I had only one lockup so far and tcp_fastretrans_alert errors happen at unknown points, I can only see if such errors appear in logs after a few days of use. I cannot be sure if it fixes the lockup.

[Lastique (andysem)]

I tried kernel 4.15.0-rc9 and had the same kind of hard lockup. The system wouldn't react to mouse or keypresses after some idle time. The log is attached (the kernel was upgraded on Jan 24-th). There are many errors about soft lockups in the log, although the backtraces are different from 4.13.

[Lastique (andysem)]

Is it possible that the lockups are caused by the buggy microcode update from Intel? Did Canonical revert the microcode update?

[Lastique (andysem)]

The errors in the kernel log don't appear with kernel version 4.10.17. However, I still get lockups with that kernel as well.

At this point I think the lockups are probably not related to the warnings and are possibly caused by a hardware failure. The errors in the log are still a valid issue, IMHO.

[Lastique (andysem)]

Just for the record, I have found the problem that caused the lockups. It was the nvidia driver ForceCompositionPipeline parameter in xorg.conf. Without it the hangs no longer happen, but the warnings are still present in the log.