Re: [RFC 0/3] Pin page control subsystem

From: Christoph Lameter
Date: Wed Aug 14 2013 - 12:48:51 EST


On Wed, 14 Aug 2013, Minchan Kim wrote:

> On Tue, Aug 13, 2013 at 04:21:30PM +0000, Christoph Lameter wrote:
> > On Tue, 13 Aug 2013, Minchan Kim wrote:
> >
> > > VM sometime want to migrate and/or reclaim pages for CMA, memory-hotplug,
> > > THP and so on but at the moment, it could handle only userspace pages
> > > so if above example subsystem have pinned a some page in a range VM want
> > > to migrate, migration is failed so above exmaple couldn't work well.
> >
> > Dont we have the mmu_notifiers that could help in that case? You could get
> > a callback which could prepare the pages for migration?
>
> Now I'm not familiar with mmu_notifier so please could you elaborate it
> a bit for me to dive into that?

Add a notifier callback for unpinning pages to the mmu notifier subsystem
and then your drivers could register with the subsystem to get
notifications when migration needs to occur etc.

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