Re: [PATCH 02/13] mm: Revalidate anon_vma in page_lock_anon_vma()

Andrew Morton
2010-05-24T19:34:03Z

On Fri, 09 Apr 2010 10:44:53 +0200
Peter Zijlstra <peterz@infradead.org> wrote:

> On Fri, 2010-04-09 at 16:29 +0900, KOSAKI Motohiro wrote:
> >
> >
> > diff --git a/mm/rmap.c b/mm/rmap.c
> > index 8b088f0..b4a0b5b 100644
> > --- a/mm/rmap.c
> > +++ b/mm/rmap.c
> > @@ -295,7 +295,7 @@ struct anon_vma *page_lock_anon_vma(struct page
> > *page)
> > unsigned long anon_mapping;
> >
> > rcu_read_lock();
> > - anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
> > + anon_mapping = (unsigned long) rcu_dereference(page->mapping);
> > if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
> > goto out;
> > if (!page_mapped(page))
>
> Yes, I think this is indeed required.
>
> I'll do a new version of the patch that includes the comment updates
> requested by Andrew.

Either this didn't happen or I lost the patch.

I parked mm-revalidate-anon_vma-in-page_lock_anon_vma.patch for now.
Hopefully everything still works without it..