reproduce:
        # https://github.com/jgunthorpe/linux/commit/b17f0e7b887fa38ca758c7b2ee98e7963f532138
        git remote add jgunthorpe https://github.com/jgunthorpe/linux
        git fetch --no-tags jgunthorpe iommu_pt
        git checkout b17f0e7b887fa38ca758c7b2ee98e7963f532138
        # choose either of the following two methods to reproduce the issue
        # 1. reproduce by kismet
           # install kmax per https://github.com/paulgazz/kmax/blob/master/README.md
           kismet --linux-ksrc=linux --selectees CONFIG_IOMMU_PT_X86PAE --selectors CONFIG_AMD_IOMMU -a=x86_64
        # 2. reproduce by make
           cd linux
           # download the config file from the "config:" link in the report, and save it as .config
           make ARCH=x86_64 olddefconfig