On Thu, Jan 31, 2019 at 09:02:03AM +0100, Christoph Hellwig wrote:
On Wed, Jan 30, 2019 at 01:50:27PM -0500, Jerome Glisse wrote:
I do not see how VMA changes are any different than using struct page in respect to userspace exposure. Those vma callback do not need to be set by everyone, in fact expectation is that only handful of driver will set those.
How can we do p2p between RDMA and GPU for instance, without exposure to userspace ? At some point you need to tell userspace hey this kernel does allow you to do that :)
To do RDMA on a memory region you need struct page backіng to start with..
No you do not with this patchset and there is no reason to tie RDMA to struct page it does not provide a single feature we would need. So as it can be done without and they are not benefit of using one i do not see why we should use one.
Cheers, Jérôme