Allow me to be mildly pedantic (sorry :)

One thing I'd like to highlight here is that remap_pfn_range() is, in the long
run, deprecated.

mmap_prepare callbacks will indicate a PFN remap mmap_action, which will do the
heavy lifting (see [0]).

So perhaps worth referring to 'PFN remapping' or something?

(Since we already have mmap_prepare() in use, it's also kinda inaccurate to
say remap_pfn_range() :)

[0]: https://www.kernel.org/doc/html/next/filesystems/mmap_prepare.html

Sorry, this is pretty nitpicky :)

Cheers, Lorenzo