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Date: Tue, 27 May 2014 09:34:22 -0500 (CDT)
From: Christoph Lameter <cl@gentwo.org>
Subject: Re: [RFC][PATCH 0/5] VM_PINNED
In-Reply-To: <20140527102909.GO30445@twins.programming.kicks-ass.net>
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References: <20140526145605.016140154@infradead.org> <CALYGNiMG1NVBUS4TJrYJMr92yWGZHSdGUdCGtBJDHoUMMhE+Wg@mail.gmail.com> <20140526203232.GC5444@laptop.programming.kicks-ass.net> <CALYGNiO8FNKjtETQMRSqgiArjfQ9nRAALUg9GGdNYbpKru=Sjw@mail.gmail.com>
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To: Peter Zijlstra <peterz@infradead.org>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>, "linux-mm@kvack.org" <linux-mm@kvack.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Andrew Morton <akpm@linux-foundation.org>, Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>, Roland Dreier <roland@kernel.org>, Sean Hefty <sean.hefty@intel.com>, Hal Rosenstock <hal.rosenstock@gmail.com>, Mike Marciniszyn <infinipath@intel.com>

On Tue, 27 May 2014, Peter Zijlstra wrote:

> The things I care about for VM_PINNED are long term pins, like the IB
> stuff, which sets up its RDMA buffers at the start of a program and
> basically leaves them in place for the entire duration of said program.

Ok that also means the pages are not to be allocated from ZONE_MOVABLE?

I expected the use of a page flag. With a vma flag we may have a situation
that mapping a page into a vma changes it to pinned and terminating a
process may unpin a page. That means the zone that the page should be
allocated from changes.

Pinned pages in ZONE_MOVABLE are not a good idea. But since "kernelcore"
is rarely used maybe that is not an issue?




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