Subject: Re: mount_union -> kernel panic
To: None <>
From: Chapman Flack <>
List: tech-kern
Date: 06/06/2006 19:21:40
theo borm wrote:
> mount_union over under
> mount_union over under
> ls under
> I know that there doesn't seem to be much point in doing mount_union
> twice (I did so by mistake), however I guess a kernel panic is a bit harsh

There may not be much point in mount_unioning /the exact same arguments/
twice, but the trouble is this kind of thing happens even when you are
doing things that would be quite useful. It seems that the current FS
layering implementation is really fragile about layering subtrees that
could have other mounts, and the current answer seems to be "don't do
that" - which unfortunately rules out many things this functionality
could be good for.

Apparently there hasn't for some time been the right combination of
annoyance with the current limitations among people with sufficient
filesystem clue to get the situation changed. I am low on the FS clue
curve myself (so far) but not on annoyance, and I would really love to
see "make the layer FSs genuinely useful" become a project, and
contribute to it what I could as well.

> debugger says:
> lockmgr: locking against myself
> stopped in pid 1465.1 (ls) at netbsd.cpu_Debugger+0x4: leave
> Does this sound familiar, anyone seen this before?