Subject: Re: [PATCH 5/5] tun: vringfd xmit support.

From: Rusty Russell <[email-masked]>
Date: Sun, 20 Apr 2008 00:41:43 +1000

On Saturday 19 April 2008 05:06:34 Andrew Morton wrote:
> On Sat, 19 Apr 2008 01:15:15 +1000 Rusty Russell <[email-masked]> 
wrote:
> > > What is the maximum numbet of pages which an unpriviliged user can
> > > concurrently pin with this code?
> >
> > Since only root can open the tun device, it's currently OK.  The old code
> > kmalloced and copied: is there some mm-fu reason why pinning userspace
> > memory is worse?
>
> We generally try to avoid it - it allows users to dos the box.

My question is: is pinning a page worse than allocating a (kernel) page in 
some way?

Cheers,
Rusty.