linux-kernel - Re: [PATCH 11/11] x86/mm, pat: convert pat tree to generic interval tree

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Date:   Mon, 7 Oct 2019 17:33:39 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Davidlohr Bueso <dave@...olabs.net>
Cc:     akpm@...ux-foundation.org, walken@...gle.com, peterz@...radead.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        dri-devel@...ts.freedesktop.org, linux-rdma@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, Davidlohr Bueso <dbueso@...e.de>
Subject: Re: [PATCH 11/11] x86/mm, pat: convert pat tree to generic interval
 tree


* Davidlohr Bueso <dave@...olabs.net> wrote:

> With some considerations, the custom pat_rbtree implementation can be
> simplified to use most of the generic interval_tree machinery.
> 
> o The tree inorder traversal can slightly differ when there are key
> ('start') collisions in the tree due to one going left and another right.
> This, however, only affects the output of debugfs' pat_memtype_list file.
> 
> o Generic interval trees are now semi open [a,b), which suits well with
> what pat wants.
> 
> o Erasing logic must remain untouched as well.
> 
> In order for the types to remain u64, the 'memtype_interval' calls are
> introduced, as opposed to simply using struct interval_tree.
> 
> In addition, pat tree might potentially also benefit by the fast overlap
> detection for the insertion case when looking up the first overlapping node
> in the tree.
> 
> Finally, I've tested this on various servers, via sanity warnings, running
> side by side with the current version and so far see no differences in the
> returned pointer node when doing memtype_rb_lowest_match() lookups.
> 
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: x86@...nel.org
> Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
> ---
>  arch/x86/mm/pat.c        |  22 +++----
>  arch/x86/mm/pat_rbtree.c | 151 ++++++++++-------------------------------------
>  2 files changed, 43 insertions(+), 130 deletions(-)

I suppose this will be carried in -mm?

If so and if this patch is regression free, then:

  Acked-by: Ingo Molnar <mingo@...nel.org>

Thanks,
	
	Ingo