リーナス・トーバルズ以下略

LKML: Linus Torvalds: Re: [BREAKAGE] Since 4.18, kernel sets SB_I_NODEV implicitly on userns mounts, breaking systemd-nspawn
https://lkml.org/lkml/2018/12/22/221

"...it is ABSOLUTELY NEVER the application that is broken. ..."