On Wed, Nov 24, 2021 at 03:14:00PM +0100, David Hildenbrand wrote: > I'm not aware of any where you can fragment 50% of all pageblocks in the > system as an unprivileged user essentially consuming almost no memory > and essentially staying inside well-defined memlock limits. But sure if > there are "many" people will be able to come up with at least one > comparable thing. I'll be happy to learn. If the concern is that THP's can be DOS'd then any avenue that renders the system out of THPs is a DOS attack vector. Including all the normal workloads that people run and already complain that THPs get exhausted. A hostile userspace can only quicken this process. > My position that FOLL_LONGTERM for unprivileged users is a strong no-go > stands as it is. As this basically excludes long standing pre-existing things like RDMA, XDP, io_uring, and more I don't think this can be the general answer for mm, sorry. Sure, lets stop now since I don't think we can agree. Jason
