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References: <1253624054-10882-1-git-send-email-mel@csn.ul.ie>
	 <1253624054-10882-3-git-send-email-mel@csn.ul.ie>
Date: Tue, 22 Sep 2009 16:38:32 +0300
Message-ID: <84144f020909220638l79329905sf9a35286130e88d0@mail.gmail.com>
Subject: Re: [PATCH 2/4] slqb: Record what node is local to a kmem_cache_cpu
From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Nick Piggin <npiggin@suse.de>, Christoph Lameter <cl@linux-foundation.org>,
       heiko.carstens@de.ibm.com, sachinp@in.ibm.com,
       linux-kernel@vger.kernel.org, linux-mm@kvack.org,
       Tejun Heo <tj@kernel.org>,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Hi Mel,

On Tue, Sep 22, 2009 at 3:54 PM, Mel Gorman <mel@csn.ul.ie> wrote:
> When freeing a page, SLQB checks if the page belongs to the local node.
> If it is not, it is considered a remote free. On the allocation side, it
> always checks the local lists and if they are empty, the page allocator
> is called. On memoryless configurations, this is effectively a memory
> leak and the machine quickly kills itself in an OOM storm.
>
> This patch records what node ID is considered local to a CPU. As the
> management structure for the CPU is always allocated from the closest
> node, the node the CPU structure resides on is considered "local".
>
> Signed-off-by: Mel Gorman <mel@csn.ul.ie>

I don't understand how the memory leak happens from the above
description (or reading the code). page_to_nid() returns some crazy
value at free time? The remote list isn't drained properly?

                        Pekka
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