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Date: Tue, 19 Jul 2011 09:33:56 -0500 (CDT)
From: Christoph Lameter <cl@linux.com>
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To: John Stultz <john.stultz@linaro.org>
cc: LKML <linux-kernel@vger.kernel.org>, Robert Love <rlove@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>, Mel Gorman <mel@csn.ul.ie>,
        Dave Hansen <dave@linux.vnet.ibm.com>, Rik van Riel <riel@redhat.com>,
        Eric Anholt <eric@anholt.net>, Jesse Barnes <jbarnes@virtuousgeek.org>
Subject: Re: [RFC][PATCH] Anonymous shared memory (ashmem) subsystem
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On Mon, 18 Jul 2011, John Stultz wrote:

> Additionally, ashmem introduces the concept of page pinning. Pinned pages (the
> default) behave like any anonymous memory. Unpinned pages are available to the
> kernel for eviction during VM pressure. When repinning the pages, the return
> value instructs user-space as to any eviction. In this manner, user-space
> processes may implement caching and similar resource management that
> efficiently integrates with kernel memory management.

Memory locking (mlock) may be a better term to use here. mlock prevents
eviction. Page pinning also prevents the movement of the pages in memory
(as needed by page migration, compaction etc).