reproduce (this is a W=1 build):
        # https://github.com/brauner/linux/commit/10a5b48c3eeb26bc4fa095dca9a6e7c4a89efdf9
        git remote add brauner-github https://github.com/brauner/linux.git
        git fetch --no-tags brauner-github vfs-6.15.async.dir
        git checkout 10a5b48c3eeb26bc4fa095dca9a6e7c4a89efdf9
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash fs/sysv/