reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git/commit/?id=64b5dfde9364204d0284d8800174ba8bb23d963f
        git remote add tytso-ext4 https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git
        git fetch --no-tags tytso-ext4 pu
        git checkout 64b5dfde9364204d0284d8800174ba8bb23d963f

        # install loongarch cross compiling tool for clang build
        # apt-get install binutils-loongarch-linux-gnu
        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=$HOME/0day COMPILER=clang-22 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=loongarch olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-22 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=loongarch SHELL=/bin/bash fs/ext4/