On Tue, Jun 11, 2024 at 11:09:15AM -0700, Mina Almasry wrote:

Just curious: in Pavel's effort, io_uring - which is not a device - is
trying to share memory with the page_pool, which is also not a device.
And Pavel is being asked to wrap the memory in a dmabuf. Is dmabuf
going to be the kernel's standard for any memory sharing between any 2
components in the future, even when they're not devices?

dmabuf is how we are refcounting non-struct page memory, there is
nothing about it that says it has to be MMIO memory, or even that the
memory doesn't have struct pages.

All it says is that the memory is alive according to dmabuf
refcounting rules. And the importer obviously don't get to touch the
underlying folios, if any.

Jason