On Fri, Dec 01, 2017 at 11:12:18AM +0100, Michal Hocko wrote: > On Thu 30-11-17 12:01:17, Jason Gunthorpe wrote: > > On Thu, Nov 30, 2017 at 10:32:42AM -0800, Dan Williams wrote: > > > > Who and how many LRU pages can pin that way and how do you prevent nasty > > > > users to DoS systems this way? > > > > > > I assume this is something the RDMA community has had to contend with? > > > I'm not an RDMA person, I'm just here to fix dax. > > > > The RDMA implementation respects the mlock rlimit > > OK, so then I am kind of lost in why do we need a special g-u-p variant. > The documentation doesn't say and quite contrary it assumes that the > caller knows what he is doing. This cannot be the right approach. I thought it was because get_user_pages_longterm is supposed to fail on DAX mappings? And maybe we should think about moving the rlimit accounting into this new function too someday? Jason