reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/c3a62066e7b934b30859a8dbe3976202bde93d16
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Muchun-Song/mm-sparse-vmemmap-Fix-vmemmap-accounting-underflow/20260421-132535
        git checkout c3a62066e7b934b30859a8dbe3976202bde93d16

        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=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash mm/