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Date: Mon, 3 Mar 2014 19:26:16 -0800
Message-ID: <CA+55aFwsjHPe4CF009p_L6PyYdP=F2bzi9-Wm5T+O6XPOCS6fg@mail.gmail.com>
Subject: Re: [PATCH v4] mm: per-thread vma caching
From: Linus Torvalds <torvalds@linux-foundation.org>
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Sender: owner-linux-mm@kvack.org
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To: Davidlohr Bueso <davidlohr@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Michel Lespinasse <walken@google.com>, Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>, KOSAKI Motohiro <kosaki.motohiro@gmail.com>, "Chandramouleeswaran, Aswin" <aswin@hp.com>, "Norton, Scott J" <scott.norton@hp.com>, linux-mm <linux-mm@kvack.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>

On Mon, Mar 3, 2014 at 7:13 PM, Davidlohr Bueso <davidlohr@hp.com> wrote:
>
> Yes, I shortly realized that was silly... but I can say for sure it can
> happen and a quick qemu run confirms it. So I see your point as to
> asking why we need it, so now I'm looking for an explanation in the
> code.

We definitely *do* have users.

One example would be ptrace -> access_process_vm -> __access_remote_vm
-> get_user_pages() -> find_extend_vma() -> find_vma_prev -> find_vma.

                    Linus

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