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Date: Wed, 23 Jan 2008 13:14:26 -0800 (PST)
From: Christoph Lameter <clameter@sgi.com>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: [PATCH] Fix boot problem in situations where the boot CPU is
	running on a memoryless node
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Cc: lee.schermerhorn@hp.com, Olaf Hering <olaf@aepfle.de>,
	Linux MM <linux-mm@kvack.org>, Mel Gorman <mel@csn.ul.ie>,
	linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Nishanth Aravamudan <nacc@us.ibm.com>, akpm@linux-foundation.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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On Wed, 23 Jan 2008, Pekka Enberg wrote:

> I think Mel said that their configuration did work with 2.6.23
> although I also wonder how that's possible. AFAIK there has been some
> changes in the page allocator that might explain this. That is, if
> kmem_getpages() returned pages for memoryless node before, bootstrap
> would have worked.

Regular kmem_getpages is called with GFP_THISNODE set. There was some 
breakage in 2.6.22 and before with GFP_THISNODE returning pages from the 
wrong node if a node had no memory. So it may have worked accidentally and 
in an unsafe manner because the pages would have been associated with the 
wrong node which could trigger bug ons and locking troubles.