Re: [RFC][PATCH 0/1] Node-based reclaim/migration

Christoph Lameter
2006-11-30T19:42:20Z

On Thu, 30 Nov 2006, Paul Menage wrote:

> On 11/30/06, Christoph Lameter <clameter@sgi.com> wrote:
> >
> > F.e. A page cache page may have mapcount == 0.
>
> OK, I was thinking just about anon pages.
>
> For pagecache pages, it's safe to access the mapping as long as we've
> locked the page, even if mapcount is 0? So we don't have the same
> races?

We have no problem with the page lock (you actually may not need any
locking since there are no references remaining to the page). The trouble
is that the vma may have vanished when we try to reestablish the pte.