reproduce:
        # https://github.com/krzk/linux/commit/8ed259002bbb28bd2cb36920e592937703a2fb8e
        git remote add krzk-github https://github.com/krzk/linux
        git fetch --no-tags krzk-github n/var-fixes
        git checkout 8ed259002bbb28bd2cb36920e592937703a2fb8e
        # 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_MFD_STMFX --selectors CONFIG_PINCTRL_STMFX -a=s390
        # 2. reproduce by make
           cd linux
           # download the config file from the "config:" link in the report, and save it as .config
           make ARCH=s390 olddefconfig