reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/commit/?id=4f6a358be27cd25e5e808031cc1715c2b6a0ef6f
        git remote add akpm-mm https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git
        git fetch --no-tags akpm-mm mm-unstable
        git checkout 4f6a358be27cd25e5e808031cc1715c2b6a0ef6f
        # choose either of the following two methods to reproduce the issue
        # 1. reproduce by kismet
           # install kmax per https://github.com/paulgazz/kmax/blob/master/README.md
           kismet --linux-ksrc=linux --selectees CONFIG_Z3FOLD --selectors CONFIG_ZSWAP_ZPOOL_DEFAULT_Z3FOLD -a=x86_64
        # 2. reproduce by make
           cd linux
           # download the config file from the "config:" link in the report, and save it as .config
           make ARCH=x86_64 olddefconfig