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

Christoph Lameter
2006-11-30T20:00:40Z

On Thu, 30 Nov 2006, Paul Menage wrote:

> On 11/30/06, Christoph Lameter <clameter@sgi.com> wrote:
> >
> > 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.
> >
>
> Why is that a problem? If the vma has gone away, then there's no need
> to reestablish the pte. And remove_file_migration_ptes() appears to be
> adequately protected against races with unlink_file_vma() since they
> both take i_mmap_sem.

We are talking about anonymous pages here. You cannot figure out
that the vma is gone since that was the only connection to the process.
Hmm... Not true we still have a migration pte in that processes space. But
we cannot find the process without the anon_vma.