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

Paul Menage
2006-11-30T18:36:00Z

On 11/30/06, Christoph Lameter <clameter@sgi.com> wrote:
> On Thu, 30 Nov 2006, Paul Menage wrote:
>
> > OK, so we could do the same, and just assume that pages with a
> > page_mapcount() of 0 are either about to be freed or can be picked up
> > on a later migration sweep. Is it common for a page to have a 0
> > page_mapcount() for a long period of time without being freed or
> > remapped?
>
> page mapcount goes to zero during migration because the references to the
> page are removed.
>

Yes, but I meant for reasons other than migration.

It sounds as though if we come across a page with page_mapcount() = 0
while gathering pages for migration, it's probably in the process of
being swapped out and so is best not to muck around with anyway?

Paul