vma
addr
pfn
Similar to vm_inert_page, this allows drivers to insert individual pages they've allocated into a user vma. Same comments apply.
This function should only be called from a vm_ops->fault handler, and in that case the handler should return NULL.
vma cannot be a COW mapping.
As this is called only for pages that do not currently exist, we do not need to flush old virtual caches or the TLB.