On Fri, Oct 13, 2017 at 8:44 AM, Dan Williams [off-list ref] wrote:

On Fri, Oct 13, 2017 at 12:12 AM, Christoph Hellwig [off-list ref] wrote:

quoted

So did we settle on the new mmap_validate vs adding a new argument
to ->mmap for real now?  I have to say I'd much prefer passing an
additional argument instead, but if higher powers rule that out
this version is ok.

MAP_DIRECT also needs the fd now, so it would be two arguments. Before
you say "that's bogus" I want to understand what the alternative looks
like for notifying userspace that its get_user_pages() registration
lease is being invalidated.

Jason straightened me out about how RDMA applications expect to get
notifications and now I see why the fd based scheme is lacking.