Intel Skylake/Kaby Lake processors: broken hyper-threading

Honestly that doesn't sound like a hyperthreading bug to me, but more like a software problem. A thousand things can cause that symptom from filesystem bugs through networking bugs through obscure dcache bugs through things like the combination of 32-bit code compiled without -D_FILE_OFFSET_BITS=64, filesystems with 64-bit inodes, and code that assumes that stat() failures must be -EEXIST and that e.g. -EOVERFLOW is impossible.