Re: [regression] commit 6a4f3b52 causes invalid memtype

[Xiaotian Feng]

On 07/05/2010 07:38 PM, Ali Gholami Rudi wrote:
> Ingo Molnar<mingo@xxxxxxx>  wrote:
> > > > > > commit 2463eb8b3093995e09a0d41b3d78ee0cf5fb4249
> > > > > > Author: Peter Zijlstra<peterz@xxxxxxxxxxxxx>
> > > > > > Date:   Sat May 29 15:31:43 2010 +0200
> > > > > >
> > > > > >        rbtree: Undo augmented trees performance damage
> > > > >
> > > > > Where can I get it?  I couldn't find it either in
> > > > > Linus' or x86 repo tip.
> > > > http://git.kernel.org/tip/2463eb8b3093995e09a0d41b3d78ee0cf5fb4249
> > >
> > > It does fix it.
> >
> > Hm, interesting. That's a pure performance fix - so why does it fix a
> > regression?
> >
> > Does Peter's augmented rbtrees improvements fix a bug too, as a side-effect?
> > If yes then we need to accelerate that commit - right now it's aimed for
> > v2.6.36.
>
> Since the bug appears after commit 6a4f3b52, it seems to be
> related to the value of memtype->subtree_max_end.  Peter's
> patch seems to change the way memtype->subtree_max_end is
> updated, which seems to fix the problem too.

Actually, this exposed a bug in augmented rbtree 
(http://lkml.org/lkml/2010/6/21/459).
With commit 6a4f3b52, the bug was easier to trigger :-)

> Thanks,
> Ali

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