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

[Christoph Lameter]

On Fri, 29 Feb 2008, Andrea Arcangeli wrote:

> > Also re the _notify variants: The binding to pte_clear_flush_young etc 
> > will become a problem for notifiers that want to sleep because 
> > pte_clear_flush is usually called with the pte lock held. See f.e. 
> > try_to_unmap_one, page_mkclean_one etc.
> 
> Calling __free_page out of the PT lock is much bigger
> change. do_wp_page will require changes anyway when the sleepable
> notifiers are merged.

I thought you wanted to get rid of the sync via pte lock?
What changes to do_wp_page do you envision?

> > It would be better if the notifier calls could be moved outside of the 
> > pte lock.
> 
> The point is that it can't make a difference right now, and my
> objective was to avoid unnecessary source code duplication (later it
> will be necessary, right now it isn't). By the time you rework
> do_wp_page, removing _notify will be a very minor detail compared to
> the rest of the changes to do_wp_page IMHO. Expanding it now won't
> provide a real advantage later.

What is the trouble with the current do_wp_page modifications? There is 
no need for invalidate_page() there so far. invalidate_range() does the 
trick there.