reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/commit/?id=c4289f5a4e563611a468b4b5379025a4aa4a7c12
        git remote add mst-vhost https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git
        git fetch --no-tags mst-vhost balloon
        git checkout c4289f5a4e563611a468b4b5379025a4aa4a7c12

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-15.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-15.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash mm/