Re: Ugly rmap NULL ptr deref oopsie on hibernate (was Linux2.6.34-rc3)
From: Minchan Kim
Date: Tue Apr 06 2010 - 12:45:51 EST
On Tue, 2010-04-06 at 09:28 -0700, Linus Torvalds wrote:
> 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;
> 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.
We always has rcu_read_lock about anon page in unmap_and_move.
So I think it's not buggy. What am I missing?
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/