Re: devfs mounted twice in linux 2.4.19-pre3

[Richard Gooch <rgooch@ras.ucalgary.ca>]

Felix Braun writes:
> Hi Richard,
> 
> I just noticed that devfs is listed twice in /proc/mounts in linux
> 2.4.19-pre3, which confuses my shutdown script. Under 2.4.19-pre my
> /proc/mounts looks like this:
> 
> devfs /dev devfs rw 0 0
> /dev/ide/host0/bus0/target0/lun0/part5 / reiserfs rw 0 0
> none /dev devfs rw 0 0
> /proc /proc proc rw 0 0
> /dev/discs/disc0/part1 /dos vfat rw 0 0
> /dev/discs/disc0/part9 /opt reiserfs rw,noatime 0 0
> none /dev/pts devpts rw 0 0
> /dev/discs/disc0/part7 /usr reiserfs rw 0 0
> none /dev/shm tmpfs rw 0 0
> 
> whereas under 2.4.18 the first line didn't show up. Is that a
> misconfiguration on my part?

No, this is due to a change in the kernel (presumably done by Al).
What seems to be happening is that the kernel temporarily mounts devfs
and then detaches it again using MNT_DETACH (actually, you need
2.4.19-pre3-ac2 to get the fix that adds MNT_DETACH). However,
detached filesystems still appear to be listed in /proc/mounts.
Arguably, this is incorrect.

If you were to reboot single-user, and with devfs=nomount, inspection
of /proc/mounts would show the line:
devfs /dev devfs rw 0 0

However, if you listed /dev, you would see that it doesn't actually
contain a devfs. Thus, /proc/mounts is deceiving you.

Al: what is the intended behaviour of MNT_DETACH wrt. /proc/mounts?

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca