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

Christoph Lameter
2008-02-27T22:39:46Z

On Wed, 20 Feb 2008, Andrea Arcangeli wrote:

> Well, xpmem requirements are complex. As as side effect of the
> simplicity of my approach, my patch is 100% safe since #v1. Now it
> also works for GRU and it cluster invalidates.

The patch has to satisfy RDMA, XPMEM, GRU and KVM. I keep hearing that we
have a KVM only solution that works 100% (which makes me just switch
ignore the rest of the argument because 100% solutions usually do not
exist).

> rcu_read_lock), no "atomic" parameters, and it doesn't open a window
> where sptes have a view on older pages and linux pte has view on newer
> pages (this can happen with remap_file_pages with my KVM swapping
> patch to use V8 Christoph's patch).

Ok so you are now getting away from keeping the refcount elevated? That
was your design decision....

> > Also, how to you resolve the case where you are not allowed to sleep?
> > I would have thought either you have to handle it, in which case nobody
> > needs to sleep; or you can't handle it, in which case the code is
> > broken.
>
> I also asked exactly this, glad you reasked this too.

It would have helped if you would have repeated my answers that you had
already gotten before. You knew I was on vacation....

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