Tangent, but 1Mb pages aren't that absurd really. The x86-64 has hardware support for 4k, 2MB, and 1GB page sizes (because each level of the pagemap cuts 9 bits from the virtual address). Luckily it supports all 3 mixed together so normally you just keep most of your data in 4kb pages and use 2Mb/1Gb occasionally. But from my understanding nothings prevents you from forcing 2Mb on all userspace code even though Linux kernel doesn't support it.