From: Jason Gunthorpe jgg@nvidia.com Sent: Wednesday, October 26, 2022 2:12 AM
Following the pattern of io_uring, perf, skb, and bpf iommfd will use user->locked_vm for accounting pinned pages. Ensure the value is included in the struct and export free_uid() as iommufd is modular.
user->locked_vm is the good accounting to use for ulimit because it is per-user, and the security sandboxing of locked pages is not supposed to be per-process. Other places (vfio, vdpa and infiniband) have used mm->pinned_vm and/or mm->locked_vm for accounting pinned pages, but this is only per-process and inconsistent with the new FOLL_LONGTERM users in the kernel.
Concurrent work is underway to try to put this in a cgroup, so everything can be consistent and the kernel can provide a FOLL_LONGTERM limit that actually provides security.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com
Reviewed-by: Kevin Tian kevin.tian@intel.com