tmpfs isn't mentioned in mount(8); all of the mount options are listed in tmpfs(4): - it should be one of the valid filesystem types. - it should be in the SEE ALSO section.
A commit references this bug: Author: skreuzer Date: Wed Aug 6 14:38:09 UTC 2014 New revision: 269627 URL: http://svnweb.freebsd.org/changeset/base/269627 Log: Mention tmpfs(5) PR: 192389 Submitted by: yaneurabeya@gmail.com Approved by: hrs (mentor) Changes: head/sbin/mount/mount.8
A commit references this bug: Author: skreuzer Date: Tue Oct 14 19:21:05 UTC 2014 New revision: 273105 URL: https://svnweb.freebsd.org/changeset/base/273105 Log: MFC r269627: Mention tmpfs(5) PR: 192389 Submitted by: yaneurabeya@gmail.com Approved by: hrs (mentor) Changes: _U stable/10/ stable/10/sbin/mount/mount.8