Re: [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

Robin Holt
2008-01-30T22:18:21Z

On Wed, Jan 30, 2008 at 11:50:26AM -0800, Christoph Lameter wrote:
> On Wed, 30 Jan 2008, Andrea Arcangeli wrote:
>
> > XPMEM requires with invalidate_range (sleepy) +
> > before_invalidate_range (sleepy). invalidate_all should also be called
> > before_release (both sleepy).
> >
> > It sounds we need full overlap of information provided by
> > invalidate_page and invalidate_range to fit all three models (the
> > opposite of the zero objective that current V3 is taking). And the
> > swap will be handled only by invalidate_page either through linux rmap
> > or external rmap (with the latter that can sleep so it's ok for you,
> > the former not). GRU can safely use the either the linux rmap notifier
> > or the external rmap notifier equally well, because when try_to_unmap
> > is called the page is locked and obviously pinned by the VM itself.
>
> So put the invalidate_page() callbacks in everywhere.

The way I am envisioning it, we essentially drop back to Andrea's original
patch. We then introduce a invalidate_range_begin (I was really thinking
of it as invalidate_and_lock_range()) and an invalidate_range_end (again
I was thinking of unlock_range).

Thanks,
Robin