OK, if this thread will be used as a reference, I'd better give a bit more info on what that line of code I pasted actually confirms:
It only confirms that your active Kernel is capable of
page table isolation - it doesn't tell you whether it was disabled at boot (I'm assuming Mint/Ubuntu haven't disabled it). To check for that you can type either of the following:
sudo grep isolation /var/log/kern.log
or
sudo grep isolation /var/log/messages
Either one should return a list of boot message lines, such as this
Jan 21 05:43:17 mx1 kernel: [ 0.000000] Kernel/User page tables isolation: enabled
that tells me that KPTI was enabled at boot this morning.
(That "mx1" is because I'm running MX Linux
)
I'm in a rush, but I'm sure someone will correct if any errors in my post