umount proc device busy?

[maxmartin]

Hello

I got a problem when being chrooted.

I do this:

mount -o rw,dev /dev/... /mnt/
chroot /mnt/hda...
mount -t proc /proc proc
apt-get remove ...
apt-get update
apt-get install
...
...
and when I finish I want to umount proc, but I got a message device busy

I can't unmount proc, so I exit chroot.

When I go to chroot again (after reboot) and when I type mount command I'll get this:

/proc/sys/fs/binfmt_misc binfmt_misc rw 0 0 (or something like this)

...but I didn't mount proc yet

How can I remove it?

What it is all about?