Suffering occasional system freezes

[ian_r_h]

OK, second attempt to post and attach.

Can't be sure it is the same problem, but this unit just refused to wake-up from a Windows-L lock-with-screen-off state (usually done by wiggling mouse and entering password).

Ctrl-Alt-F1 (wait), then Ctrl-Alt-F7 failed,
Alt-Sysrq R E I S U B failed,
Ctrl-Alt-Del failed,
Tap power button failed.

Had to hard reset.

Tying to attach today's syslog and xorg logs...

[ian_r_h]

Addendum:

So, newbie here,  alt-sysrq R E I S U B may not be working for me because I have not been HOLDING alt-sysrq while pressing in turn R E I S U B.

Correct me if I'm wrong - but as I'm reading it the correct process is to HOLD alt-sysrq while pressing in turn R E I S U B (with pauses between each of those letters)?

Also, Ubuntu only has S U B enabled by default as I understand it (though I did enable all options, and hopefully wrote how above as I now can't recall it)!

[TheDead]

When you have a system freeze, tap the Caps Lock key a few times. If the CapsLock light does not turn on or off, you can't type anything with the keyboard usually, the computer itself has crashed...
If nothing move and mouse is frozen too of course.

The problem seems to be hardware at first glance. Can you check in the BIOS for the powersupply voltages (3v,5v,12v,etc.)? Then check temperatures either in BIOS or Linux.
Also, if you can open the computer physically and check if some capacitors or "bumped" and/or have leaked.
This is mainly for PC's and not laptops though.

I also saw electrical troubles leading to this kind of problem. An AC, Toaster, Heater or Microwave on same electrical circuit for exemple.

Software wise, maybe trying to use the computer off a live USB Linux for a day?

Good luck and Merrrry Chrrristmas!

[trinidad]

How did you install this system? Did you allow the installer to partition the drive, or did you use gparted first? Disk entries in the report appear wrong.

Open >Menu>System>Partition Drives in the LL system in question and post a screenshot of your drive partitioning scheme.

TC

[ian_r_h]

Thanks TheDead and Trinidad.

It's getting close to my leaving to my parents for Christmas, so I'll have to pick this up afterwards.

I'll look for a temperature measuring app for LL.  I'll also set up the recommended image posting after xmas too.

Meanwhile, to answer your Trinidad sans-screenshot I installed using the default options except that I encrypted the whole drive.  GParted lists the following partitions:-

/dev/sda1 | ext2 | /boot | 487.00 MiB | 130.48MiB used | 356.52 MiB unused | Boot flag
/dev/sda2 | extended | | 465.28 GiB | --- used | --- unused | No flag
  /dev/sda5 | crypt-luks | | 465.28 GiB | --- used | --- unused | No flag
unallocated | unallocated | | 1.02 MiB | --- used | --- unused | No flag

/dev/sda1 has a "calculator" icon next to it,
/dev/sda5 has a "! in a speech bubble" icon next to it.

[trinidad]

Have a good Christmas.

TC

[ian_r_h]

Hi, all,

I've got to a point now where I can begin to report back what I've found, as much in case my findings are useful to someone else, as for myself.  I haven't experienced any system freeze since (i) ceasing to use task manager unless absolutely necessary, and (ii) no longer turning off bluetooth from the default option and (iii) turning on the laptop's internal monitor (while I actually am using the external monitor.)  Kernel 4.4.0-generic 101 and 102 are the versions which seem affected in LL 3.6 (64-bit).

Technical Summary.
================

Symptom:  Linux Lite kernel 4.4.0-generic 101 and 102 (no later version yet tested) experiences total system freezes requiring hard reset (with a mean time between failures of about 16 hours).  No syslog error messages generated, system simply locks up randomly.

Main variables in play:-
BIOS vendor:  American Megatrends Inc.
BIOS version:  5.11 (03/30/2016)
Base Motherboard:  CLEVO W94_95_97JU
CPU architecture:  Intel Core i3-6100U (Sky Lake) 2.3GHz x86_64 (Family 6, Model 78)
GPU architecture:  Sky Lake Integrated Graphics (Intel) ID: 2, version: 07 (i915)
GPU driver:  ? (no proprietary driver installed by choice - xorg-server 2:1.18.4-0ubuntu0.7)
LL version:  3.6 (64bit)
Kernel version:  4.4.0-generic #x (OK *prior* to version 4.4.0-generic 101); current installed is 102, also affected.
Triggering application:  Task Manager (most likely); possibly blueman applet with bluetooth turned off or laptop internal monitor disabled.

Brief Summary.
=============

The triggering application is most likely Task Manager.  I was running this permanently in the background both in earlier Kernel versions not experiencing system freezes and those which have done so.  I then stopped performing any updates, and systematically stopped using each application in turn during which system freezes had occurred.  Three applications and one usage configuration remain suspect:-

1)  Task Manager.  This continuously updates, including plotting of graphs.  During every system freeze (including one with the computer locked - windows-L - and screens off) task manager was running.  Since no longer running task manager, no system freezes have occurred.  My hunch is that this is most likely the triggering application.
2)  Blueman applet.  I had routinely been disabling bluetooth immediately after booting up using the panel icon.  Since stopping doing so (coincident with no longer using task manager), no system freezes have occurred.
3)  Operating an external monitor with laptop internal monitor turned off; MORE LIKELY:  Just with the internal monitor turned off.  (I have also stopped locking the laptop for now.)

Additional Note.
==============

Prior to updating to kernel 4.4.0-generic 101, and with task manager running and bluetooth disabled, I had been experiencing momentary instability which coincided with syslog reports that the GPU engine had hung and been reset (stuck on render ring ... GPU HANG: ecode 9:0:0x84dffff8, in Xorg [1251]).  It seems plausible that this could be related in some way, except that one system freeze subsequent to updating to kernel 4.4.4-generic 101 occurred with the screens off during a windows-L system lock (and before I attempted to unlock the laptop).

Common causes suggested with kernel 4.4.x Ubuntu system freezes (search "freeze ubuntu skylake") is the C-State bug in the Sky Lake family of Intel processors.  I cannot rule this out.  It seems also plausible that the processes continually called by task manager (even with system windows-L locked) are causing the CPU to enter or leave this triggering state.  But it is beyond my current technical knowledge to attempt to falsify this hypothesis.

One other triggering state may be the use of an external monitor, with the internal monitor on the laptop disabled.  No system freeze has occurred since re-enabling the internal monitor as well.  Given the windows-L lock state had both monitors disabled, it would seem that it would have to be more likely the state of using the laptop simply with the internal monitor turned off.

Conclusion
=========

As far as I am concerned, pending the problem starting up again, for me the issue is solved.  I am satisfied that the most likely trigger was something task manager was doing, and so not running task manager has either prevented the issue recurring or else greatly increased the mean time between system freezes.  The other most likely possibility is that simply re-enabling the laptop's internal monitor (possibly while also using the external monitor as my main one) has solved the problem.

I note that most of the problems experienced with system freezes (but not all) in Internet searches were from users of kernel 4.4.x where a kernel was specified.  This may suggest that this kernel series (v4.4.x) is buggy in certain commonly experienced circumstances.

[trinidad]

Please open >Menu>System>Parttion Drives and post a screenshot, or post the contents of fstab from within the LL system up and running. Externally mounted (media channel) gparted will not show informative results because of LUKS. I am not satisfied that swap is correctly configured on your machine.

TC

[ian_r_h]

Thanks, TC,

I've taken a screenshot, but will have to read up on how to get it uploaded here...

[ian_r_h]

Menu>System>Parttion Drives displays as follows:-



Process for installing LL was as follows:-

1) Boot and insert live DVD (currently version 3.6 64-bit)
2) Restart (CTRL-ALT-DEL)
3) Boot from Live DVD and select Live option
4) Connect to the Internet
5) Change software repos to local
6) Start the Install Linux Lite app
English
DO NOT download anything while installing!
Erase disk and install + encrypt for security
Enter encryption key + overwrite empty disk space
Locale:  London
English keyboard with extended WinKeys
Enter ID, etc.  + DO NOT encrypt home folder
Remove install media when prompted
7) Boot from HD at restart

(and so on).

Essentially, following the default installation instructions here, except for choosing to encrypt entire hard disk (and not to encrypt home folder).