reproduce (this is a W=1 build):
        git remote add kleikamp-shaggy https://github.com/kleikamp/linux-shaggy
        git fetch kleikamp-shaggy jfs-next
        git checkout kleikamp-shaggy/jfs-next
        b4 shazam https://lore.kernel.org/r/20240130055414.2143959-2-willy@infradead.org
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash mm/