On 2019-01-30 10:44 a.m., Jason Gunthorpe wrote: > I don't see why a special case with a VMA is really that different. Well one *really* big difference is the VMA changes necessarily expose specialized new functionality to userspace which has to be supported forever and may be difficult to change. The p2pdma code is largely in-kernel and we can rework and change the interfaces all we want as we improve our struct page infrastructure. I'd also argue that p2pdma isn't nearly as specialized as this VMA thing and can be used pretty generically to do other things. Though, the other ideas we've talked about doing are pretty far off and may have other challenges. Logan
