My 4.9.75 Ubuntu machine just went fubar too. Threads literally lock up on my E5-1660 on kernel 4.9.75. All non KPTI kernels are fine, but the KPTI patches causes programs to cause the kernel to fully freeze. It’s not panicing, cause multimedia streams still work, but it’s literally 100% frozen without panicing. A “hard” soft lock.
Went back to 4.13.16 and all was well again. This is a direct impact of the KPTI patches.
Fedora was on the kernel just before KPTI and didn’t release KPTI just yet I think for this specific reason. Also, make sure to get 384.111 Nvidia drivers for 4.14.11 or you risk not being able to boot.
If Page Table Isolation is causing soft hard locks on everything but Haswell and up, that’s just absolutely absurd.