reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # https://github.com/intel-lab-lkp/linux/commit/456289e0bd14ced4522a60d0f8f0b9016a4ba29e
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review NeilBrown/nfs-change-mkdir-inode_operation-to-return-alternate-dentry-if-needed/20250214-141741
        git checkout 456289e0bd14ced4522a60d0f8f0b9016a4ba29e
        # 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=um olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=um SHELL=/bin/bash fs/hostfs/