Re: [RFC PATCH 3/3] mm/map_contig: Add mmap(MAP_CONTIG) support

[Michal Hocko]

On Fri 13-10-17 10:20:06, Cristopher Lameter wrote:
> On Fri, 13 Oct 2017, Michal Hocko wrote:
[...]
> > I am not really convinced this is a good interface. You are basically
> > trying to bypass virtual memory abstraction and that is quite
> > contradicting the mmap API to me.
> 
> This is a standardized posix interface as described in our presentation at
> the plumbers conference. See the presentation on contiguous allocations.

Are you trying to desing a generic interface with a very specific and HW
dependent usecase in mind?
 
> The contiguous allocations are particularly useful for the RDMA API which
> allows registering user space memory with devices.

then make those devices expose an implementation of an mmap which does
that. You would get both a proper access control (via fd), accounting
and others.
-- 
Michal Hocko
SUSE Labs