[PATCH v2 1/1] arm64: mm: correct the inside linear map boundaries during hotplug check

[Pavel Tatashin]

> Can't we simply use signed arithmetic here? This expression works fine
> if the quantities are all interpreted as s64 instead of u64

I was thinking about that, but I do not like the idea of using sign
arithmetics for physical addresses. Also, I am worried that someone in
the future will unknowingly change it to unsigns or to phys_addr_t. It
is safer to have start explicitly set to 0 in case of wrap.