auth.logで、pam_unix(cron:session): session opened for user root みたいなメッセージがずっと出ててうっとおしいやつ

/var/log/auth.log にて、CRONが動くときこういうログがずーっと出てて超うっとおしいやつ

Oct 24 19:28:01 unkoman CRON[22792]: pam_unix(cron:session): session opened for user root by (uid=0)
Oct 24 19:28:02 unkoman CRON[22792]: pam_unix(cron:session): session closed for user root
Oct 24 19:29:01 unkoman CRON[22918]: pam_unix(cron:session): session opened for user root by (uid=0)
Oct 24 19:29:01 unkoman CRON[22918]: pam_unix(cron:session): session closed for user root

おまじないとしか言いようのない設定追加でなんとかなることがわかった

`/etc/pam.d/common-session-noninteractive`

   # here are the per-package modules (the "Primary" block)
   session [default=1]                     pam_permit.so
   # here's the fallback if no module succeeds
   session requisite                       pam_deny.so
   # prime the stack with a positive return value if there isn't one already;
   # this avoids us returning an error just because nothing sets a success code
   # since the modules above will each just jump around
   session required                        pam_permit.so
   # and here are more per-package modules (the "Additional" block)
★ session [success=1 default=ignore] pam_succeed_if.so service in cron quiet use_uid
   session required        pam_unix.so

session [success=1 default=ignore] pam_succeed_if.so service in cron quiet use_uid を、
session required pam_unix.so の前に追記する
そして、設定変更後は cron を再起動。原理はマジでわからん。