Re: [patch] x86, pat: freeing invalid memtype messages

[Xiaotian Feng]

On 06/22/2010 01:54 AM, Suresh Siddha wrote:
> On Mon, 2010-06-21 at 08:41 -0700, Peter Zijlstra wrote:
> > On Mon, 2010-06-21 at 17:33 +0200, Marcin Slusarz wrote:
> > > On Mon, Jun 21, 2010 at 07:07:27PM +0800, Xiaotian Feng wrote:
> > > > On 06/21/2010 07:02 PM, Peter Zijlstra wrote:
> > > > > On Mon, 2010-06-21 at 18:56 +0800, Xiaotian Feng wrote:
> > > > >
> > > > > > I guess there might be something wrong between the augmented rbtree insert/remove ..
> > > > >
> > > > > The easiest thing is to revert that change and try again, the next step
> > > > > would be to print the full RB tree on each modification and look where
> > > > > it goes wrong.
> > > > >
> > > > > That said, I did print my fair share of (augmented) RB trees while
> > > > > playing with scheduler patches and I can't remember it ever having
> > > > > messed up like that.
> > > > He's using 2.6.35-rc2+, without your "rbtree: Undo augmented trees
> > > > performance damage" patch ;-)
> > >
> > > I applied it manually (commit 2463eb8b3093995e09a0d41b3d78ee0cf5fb4249 from -tip)
> > > to 2.6.35-rc3 and it fixed both acpi's and nouveau's "invalid memtype" messages.
> > > Thanks.
> >
> > Oh neat, so it actually fixes a bug in the previous augmented rb-tree
> > implementation?
>
> When I was reviewing your fix, it looked like that prior to your fix we
> were re-augmenting only at points where we do the tree rotations/color
> change and at the points of node insertion/removal. I don't think we
> were re-augmenting all the parent nodes in the path of the selected-node
> that is going to replace the deleted node.
>
> Perhaps we were hitting this issue here.

Were it from a insert without any rotations/color changes?

This case is performing insert A/remove A/ 2nd insert A/ 2nd remove 
A/3rd insert A. And the 2nd remove
shows us the invalid memtype.  3rd insert shows us it is in the rbtree. 
All I can image is that get_subtree_max_end
in memtype_rb_lowest_match returned stale value.

It looks like we don't re-augment the parent nodes if there aren't any 
rotations/color changes
in the rb_insert_color().

> thanks,
> suresh

--
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/