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

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Message-ID: <AANLkTilXM-6fIvU8TYADyyxxyg-6eIclkzfeT4vvBVJY@mail.gmail.com>
Date:	Mon, 21 Jun 2010 11:08:50 -0700
From:	Venkatesh Pallipadi <venki@...gle.com>
To:	Suresh Siddha <suresh.b.siddha@...el.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Marcin Slusarz <marcin.slusarz@...il.com>,
	Xiaotian Feng <dfeng@...hat.com>,
	Dan Carpenter <error27@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, "H.PeterA" <nvinhpa@...or.com>,
	Jack Steiner <steiner@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>
Subject: Re: [patch] x86, pat: freeing invalid memtype messages

On Mon, Jun 21, 2010 at 10:54 AM, Suresh Siddha
<suresh.b.siddha@...el.com> 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.
>

rb_erase was calling the augment callback with successor_parent_cb.
That should be doing proper re-augmenting on delete.

May be we are hitting the problem with not-initializing
subtree_max_end on insert? That was fixed in a later patch.

Thanks,
Venki
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