nvidia-peermem "Invalid argument" on Ubuntu — Fix GPUDirect RDMA with DMA-BUF TL;DR: If modprobe nvidia-peermem fails with Invalid argument ( -EINVAL ) on a system using the inbox Ubuntu InfiniBand stack ( rdma-core ), the module is not broken and you do not need it. nvidia-peermem requires an API that only exists in MLNX_OFED. On Hopper/Blackwell GPUs with the NVIDIA open driver, use DMA-BUF instead — it does GPUDirect RDMA natively. The one gotcha: you must enable nvidia-drm modeset=1 . Applie