> + if (ubuf->subpgoff) {
> + pfn += ubuf->subpgoff[pgoff] >> PAGE_SHIFT;
> + }
No need for the braces here..
> @@ -253,16 +271,59 @@ static long udmabuf_create(struct miscdevice *device,
> goto err;
> pgoff = list[i].offset >> PAGE_SHIFT;
> pgcnt = list[i].size >> PAGE_SHIFT;
> + if (is_file_hugepages(memfd)) {
> + if (!ubuf->subpgoff) {
> + ubuf->subpgoff = kmalloc_array(ubuf->pagecount,
> + sizeof(*ubuf->subpgoff),
Overly long line here.
Given how much code there is in the main loop here this almost screams
for splitting that into a helper anyay.
And then the body of the pgidx loop below which is compeltely different
for hugetlb vs not ask for another helper each for the loop body
variants.
