>
> On Wed, 7 Apr 2010, Minchan Kim wrote:
> > >
> > > However, that made me look at the PAGE_MIGRATION case. That seems to be
> > > just broken. It's doing that page_anon_vma() + spin_lock without holding
> > > any RCU locks, so there is no guarantee that anon_vma there is at all
> > > valid.
> >
> > FYI, recently there is a patch about migration case.
> >
http://lkml.org/lkml/2010/4/2/145
>
> No, I'm talking about rmap_walk_anon():
>
> anon_vma = page_anon_vma(page);
> if (!anon_vma)
> return ret;
> spin_lock(&anon_vma->lock);
>
> which seems to be simply buggy. The anon_vma may not exist any more,
> because an RCU event might have really freed the page between looking it
> up and locking it.
>
> Linus
