[$] Software-tag-based KASAN

The kernel address sanitizer (KASAN) is akernel debugging tool meant to catch incorrect use of kernel pointers. Itis an effective tool, if the number of KASAN-based bug reports showing upon the mailing lists is any indication. The downside of KASAN is asignificant increase in the amount of memory used by a running system. Thesoftware-tag-basedmode proposed by Andrey Konovalov has the potential to address thatproblem, but it brings some limitations of its own.