reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git/commit/?id=2e6275cf004188e749d79ba9b357ab47a94c4bfd
        git remote add tglx-devel https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git
        git fetch --no-tags tglx-devel irq/core
        git checkout 2e6275cf004188e749d79ba9b357ab47a94c4bfd

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash fs/nfsd/ kernel/irq/