Re: [PATCH v8 1/5] mm: introduce a common interface for balloonpages mobility

[Michael S. Tsirkin]

On Tue, Aug 21, 2012 at 04:23:58PM -0300, Rafael Aquini wrote:
> On Tue, Aug 21, 2012 at 10:13:30PM +0300, Michael S. Tsirkin wrote:
> > > 
> > > I believe rcu_dereference_protected() is what I want/need here, since this code
> > > is always called for pages which we hold locked (PG_locked bit).
> > 
> > It would only help if we locked the page while updating the mapping,
> > as far as I can see we don't.
> >
> 
> But we can do it. In fact, by doing it (locking the page) we can easily avoid
> the nasty race balloon_isolate_page / leak_balloon, in a much simpler way, IMHO.

Absolutely. Further, we should look hard at whether most RCU uses
in this patchset can be replaced with page lock.

-- 
MST
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