Reading the Code Around Make_u32_from_two_u16()

This blogpost comments on Linus's latest tirade by reading the code.

For example, it explains the specific problem of technical debt on failing to mask of high order bits by casting the low part to (u16). Years from now, when this leads to a bug, you'll no longer be able to fix the macro because inevitable some code will by that time depend upon high order bits in the low part.