On Mon, Jun 17, 2024 at 07:04:43PM +0100, Pavel Begunkov wrote:

quoted

There should be no other memory source other than the page allocator
and dmabuf.  If you need different life time control for your
zero copy proposal don't mix that up with the contol of the memory
source.

No idea how I'm mixing it up when I was explaining exactly this
all along as well as that the callback (and presumably the call
site in general) you was so eager to nack is used exactly to
implement the life time control.

And that's exactly my point.  You want to use one callback to mix
allocation source and life time control.  That's the perfect recipe
to create an un-extensible un-composable mess.