On Wed, Jun 12, 2019 at 5:09 AM Jan Kara <jack@xxxxxxx> wrote: > > On Wed 12-06-19 08:47:21, Jason Gunthorpe wrote: > > On Wed, Jun 12, 2019 at 12:29:17PM +0200, Jan Kara wrote: > > > > > > > The main objection to the current ODP & DAX solution is that very > > > > > little HW can actually implement it, having the alternative still > > > > > require HW support doesn't seem like progress. > > > > > > > > > > I think we will eventually start seein some HW be able to do this > > > > > invalidation, but it won't be universal, and I'd rather leave it > > > > > optional, for recovery from truely catastrophic errors (ie my DAX is > > > > > on fire, I need to unplug it). > > > > > > > > Agreed. I think software wise there is not much some of the devices can do > > > > with such an "invalidate". > > > > > > So out of curiosity: What does RDMA driver do when userspace just closes > > > the file pointing to RDMA object? It has to handle that somehow by aborting > > > everything that's going on... And I wanted similar behavior here. > > > > It aborts *everything* connected to that file descriptor. Destroying > > everything avoids creating inconsistencies that destroying a subset > > would create. > > > > What has been talked about for lease break is not destroying anything > > but very selectively saying that one memory region linked to the GUP > > is no longer functional. > > OK, so what I had in mind was that if RDMA app doesn't play by the rules > and closes the file with existing pins (and thus layout lease) we would > force it to abort everything. Yes, it is disruptive but then the app didn't > obey the rule that it has to maintain file lease while holding pins. Thus > such situation should never happen unless the app is malicious / buggy. When you say 'close' do you mean the final release of the fd? The vma keeps a reference to a 'struct file' live even after the fd is closed.
