reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://github.com/sean-jc/linux/commit/c7de2d2c0cab7d890294b5437faf1bccb6bc978d
        git remote add sean-jc https://github.com/sean-jc/linux
        git fetch --no-tags sean-jc x86/cleanup_smp_nmi_shootdown
        git checkout c7de2d2c0cab7d890294b5437faf1bccb6bc978d
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-18 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=i386 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-18 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash arch/x86/kernel/