Re: [PATCH] rmap: add exclusively owned pages to the newestanon_vma

[Borislav Petkov]

From: Rik van Riel <riel@xxxxxxxxxx>
Date: Wed, Apr 14, 2010 at 05:59:28PM -0400

> The recent anon_vma fixes cause many anonymous pages to end up
> in the parent process anon_vma, even when the page is exclusively
> owned by the current process.
> 
> Adding exclusively owned anonymous pages to the top anon_vma
> reduces rmap scanning overhead, especially in workloads with
> forking servers.
> 
> This patch adds a parameter to __page_set_anon_rmap that can
> be used to indicate whether or not the added page is exclusively
> owned by the current process.
> 
> Pages added through page_add_new_anon_rmap are exclusively
> owned by the current process, and can be added to the top
> anon_vma.
> 
> Pages added through page_add_anon_rmap can be either shared
> or exclusively owned, so we do the conservative thing and
> add it to the oldest anon_vma.
> 
> A next step would be to add the exclusive parameter to
> page_add_anon_rmap, to be used from functions where we do
> know for sure whether a page is exclusively owned.
> 
> Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
> ---
> Borislav, I audited the code before making this change, but would
> still appreciate your testing of this patch :)

Just did some light hammering and it looks ok so far. I'll keep watching
out for oopsies/issues.

Lightly-tested-by: Borislav Petkov <bp@xxxxxxxxx>

-- 
Regards/Gruss,
    Boris.
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