which is exactly what malloc is already doing for, thus my point is by using malloc we would fullfill your request.

But do you have an actual real work application where this would help?
it is pretty easy to figure out, just run the application under perf and see if there is a relevant amount of time spent in page_fault/clear_pages.

And as mentioned you can already change the allocator for arenas at runtime, so you could also try changing it to malloc and see if your application gets any faster.