[PATCH v4] mm: introduce reference pages

[Matthew Wilcox]

On Tue, Jun 29, 2021 at 12:19:22AM -0700, John Hubbard wrote:
> > +SYSCALL_DEFINE2(refpage_create, const void *__user, content, unsigned long,
> > +		flags)
> 
> From the API discussion (and using a simpler syntax to illustrate this), it
> seems like the following would be close:
> 
> enum content_type {
> 	BYTE_PATTERN,
> 	FOUR_BYTE_PATTERN,
> 	...
> 	FULL_4KB_PAGE
> };
> 
> int refpage_create(const void *__user content, enum content_type, unsigned long flags);
> 
> ...and if content_type == BYTE_PATTERN, then content is a pointer to just one byte of
> data, and so forth for the other enum values.

That seems a little more complicated and non-extensible.

int refpage_create(const void *__user content, unsigned int size,
		unsigned long flags);