Comment 4 for bug 2064144

@mbelair:

  the rule is accepted by the parser, and has been since mount rules have been supported. So this is a case of it may not be to spec, but it is not new and existed as such for a long time. So just like

  mount (rbind) /foo,

we need to support this. That is to say we make every effort not to break existing userspace unless necessary. IF its bug that we catch when we first ship the feature, yes fix and follow spec, a bug like this however. We don't break existing userspace.

As a side note, logprof/genprof exiting because they can't parse a rule is bad, and a behavior that needs to be fixed as well.

Actually the sentence isn't invalid, the original mount rules did not restrict source to be a path, and there are ways to use mount where the source isn't a path. Any addition to the man page claim source must be a path is wrong. Admittedly it is almost always a path, but there are in fact cases where it isn't. But I agree it should be removed because as options are introduced they will get left off and it will be confusing.