01-09-2018, 12:01 PM
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.
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.
Don't worry about artificial intelligence. Worry about natural stupidity. 