kidle_inject causing very high load
It appears that this is a bug in the kernel.
From the comments on that bug report, running the command
sudo rmmod intel_powerclamp seems to have stopped the
kidle_inject processes and I haven't noticed any issues with doing so as of yet.
Hopefully this will be fixed soon. If I do notice anything I will update this answer.
rmmod command needs to be run every time you boot the machine. I have not noticed anything bad happening since running this command.
I have noticed since doing this that my CPU temp now tends to run much lower at around the ~72°
For making this set while booting use a command
echo "blacklist intel_powerclamp" > /etc/modprobe.d/disable-powerclamp.conf
The accepted answer is incomplete. According to the bug comments, the kidle_inject processes are spawned to throttle processor and protect it from further overheating.
Before "fixing" the bug, make sure your fan is clean and works correctly. I had this problem and found out that the vent was full of dust. After cleaning and reboot no kidle_inject was spawned anymore.
If you are running a macbook, make sure that you have
macfanctld installed. If you don't, the fan will be fixed at around 2000 RPM out of the max 6000. This can be seen by the
sensors command. In this situation powerclamp will kick in to save the CPUs rather early.