reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git/commit/?id=995b3d5f04ba947ebb9fbab377f937ae9036efea
        git remote add leon-rdma https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git
        git fetch --no-tags leon-rdma ipsec-fixes
        git checkout 995b3d5f04ba947ebb9fbab377f937ae9036efea
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=x86_64 olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/gpu/drm/i915/ drivers/net/ethernet/mellanox/mlx5/core/