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Date: Thu, 29 May 2014 10:01:34 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Christoph Lameter <cl@linux.com>, Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>,
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        Hal Rosenstock <hal.rosenstock@gmail.com>,
        Mike Marciniszyn <infinipath@intel.com>
Subject: Re: [RFC][PATCH 1/5] mm: Introduce VM_PINNED and interfaces
Message-ID: <20140529080134.GC30445@twins.programming.kicks-ass.net>
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On Wed, May 28, 2014 at 09:48:43PM -0400, Rik van Riel wrote:
> On 05/26/2014 10:56 AM, Peter Zijlstra wrote:
>=20
> >  include/linux/mm.h       |    3 +
> >  include/linux/mm_types.h |    5 +
> >  kernel/fork.c            |    2=20
> >  mm/mlock.c               |  133 ++++++++++++++++++++++++++++++++++++++=
++++-----
> >  mm/mmap.c                |   18 ++++--
> >  5 files changed, 141 insertions(+), 20 deletions(-)
>=20
> I'm guessing you will also want a patch that adds some code to
> rmap.c, madvise.c, and a few other places to actually enforce
> the VM_PINNED semantics?

Eventually, yes. As it stands they're not needed, because perf pages
aren't in the pagecache and IB goes a big get_user_pages() and the
elevated refcount stops everything dead.

But yes, once we go do fancy things like migrate the pages into
UNMOVABLE blocks, then we need to have VM_PINNED itself mean something,
instead of it describing something.

But before we go down there, I'd like to get the IB bits sorted and
general agreement on the path.

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