[ofa-general] Re: [kvm-devel] [PATCH] mmu notifiers #v7

[Andrea Arcangeli]

On Wed, Feb 27, 2008 at 04:08:07PM -0800, Christoph Lameter wrote:
> On Thu, 28 Feb 2008, Andrea Arcangeli wrote:
> 
> > If RDMA/IB folks needed to block in invalidate_range, I guess they
> > need to do so on top of tmpfs too, and that never worked with your
> > patch anyway.
> 
> How about blocking in invalidate_page()? It can be made to work...

Yes, it can be made to work with even more extended VM changes than to
only allow invalidate_range to schedule. Those core VM changes should
only be done "by default" (w/o CONFIG_XPMEM=y), if they're doing good
to the VM regardless of xpmem requirements. And I'm not really sure of
that. I think they don't do any good or they would be a mutex
already...

> Well so we do not address the issues?

I'm not suggesting not to address the issues, just that those issues
requires VM core changes, and likely those changes should be
switchable under a CONFIG_XPMEM, so I see no reason to delay the mmu
notifier until those changes are done and merged too. It's kind of a
separate problem.

> Either that or a separate rmap as also mentioned before.

DRI also wants invalidate_page by (mm,addr).