On Wed, Nov 09, 2011 at 10:47:45AM +0900, KIMURA Masaru wrote:
>
> Same here on my Gentoo and Ubuntu 11.10.
> "# mount /sys" does fail and warn "already mounted" but "# mount /dev" doesn't.
>
> First of all, /dev is mounted on tmpfs which is a filesystem on memory.
> And /sys is mounted on sysfs which is another filesystem on memory.
Yes, this normal filesystem specific behavior.
[...]
> Summary:
> - "# mount /dev" hides udev managed /dev.
> - because it doesn't return a busy error.
> - because it uses tmpfs.
> - using tmpfs, we are not able to treat this case as error in kernel.
Sure, it's not a bug.
It would be nice to have mount option (VFS flag) to control this behavior,
something like:
# mount -t tmpfs none /dev -o nooverlay
# mount -t tmpfs none /dev --> EBUSY
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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