Kernel heap attacks frequently depend on being able to create
specifically-sized allocations with user-controlled contents
that will be allocated into the same kmalloc bucket as a
target object. To avoid sharing these allocation buckets,
provide an explicitly separated set of buckets to be used for
user-controlled allocations. This may very slightly increase
memory fragmentation, though in practice it's only a handful
of extra pages since the bulk of user-controlled allocations
are relatively long-lived.

If unsure, say Y.