On Fri, Oct 09, 2020 at 10:48:55AM -0400, Chuck Lever wrote: > Hi Jason- > > > On Oct 9, 2020, at 10:39 AM, Jason Gunthorpe <jgg@xxxxxxxx> wrote: > > > > On Fri, Oct 09, 2020 at 12:49:30PM +0800, Ka-Cheong Poon wrote: > >> As I mentioned before, this is a very serious restriction on how > >> the RDMA subsystem can be used in a namespace environment by kernel > >> module. The reason given for this restriction is that any kernel > >> socket without a corresponding user space file descriptor is "rogue". > >> All Internet protocol code create a kernel socket without user > >> interaction. Are they all "rogue"? > > > > You should work with Chuck to make NFS use namespaces properly and > > then you can propose what changes might be needed with a proper > > justification. > > The NFS server code already uses namespaces for creating listener > endpoints, already has a user space component that drives the > creation of listeners, and already passes an appropriate struct > net to rdma_create_id. As far as I am aware, it is namespace-aware > and -friendly all the way down to rdma_create_id(). > > What more needs to be done? I have no idea, if you are able to pass a namespace all the way down to the listening cm_id and everything works right (I'm skeptical) then there is nothing more to worry about - why are we having this thread? > > The rules for lifetime on IB clients are tricky, and the interaction > > with namespaces makes it all a lot more murky. > > I think what Ka-cheong is asking is for a detailed explanation of > these lifetime rules so we can understand why rdma_create_id bumps > the namespace reference count. It is because the CM has no code to revoke a CM ID before the namespace goes away and the pointer becomes invalid. Jason
