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From: Robin Holt <holt@sgi.com>
To: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Mike Kravetz <kravetz@us.ibm.com>,
	linux-mm@kvack.org, Andy Whitcroft <apw@shadowen.org>,
	Anton Blanchard <anton@samba.org>,
	linux-kernel@vger.kernel.org
Subject: Re: pfn_to_nid under CONFIG_SPARSEMEM and CONFIG_NUMA
Date: Wed, 16 Nov 2005 07:00:24 -0600	[thread overview]
Message-ID: <20051116130024.GD4573@lnx-holt.americas.sgi.com> (raw)
In-Reply-To: <20051116115548.EE18.Y-GOTO@jp.fujitsu.com>

On Wed, Nov 16, 2005 at 12:14:18PM +0900, Yasunori Goto wrote:
> static inline int pfn_to_nid(unsigned long pfn)
> {
> 	return page_to_nid(pfn_to_page(pfn));

But that does not work if the pfn points to something which does not
have a struct page behind it (uncached memory on ia64 for instance).
At the very least you would need to ensure pfn_to_page returns a  struct
page * before continuing blindly.

> page_to_nid() and pfn_to_page() is well defined.
> Probably, this will work on all architecture.
> So, just we should check this should be used after that memmap
> is initialized.

Robin

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  reply	other threads:[~2005-11-16 13:00 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-11-15 22:10 Mike Kravetz
2005-11-16  3:14 ` Yasunori Goto
2005-11-16 13:00   ` Robin Holt [this message]
2005-11-16 13:25 ` Andy Whitcroft
2005-11-16 22:59 ` [PATCH 0/3] SPARSEMEM: pfn_to_nid implementation Andy Whitcroft
2005-11-16 23:00   ` [PATCH 1/3] kvaddr_to_nid not used in common code Andy Whitcroft
2005-11-16 23:00   ` [PATCH 2/3] pfn_to_pgdat " Andy Whitcroft
2005-11-16 23:00   ` [PATCH 3/3] sparse provide pfn_to_nid Andy Whitcroft
2005-11-20  7:31     ` Andrew Morton
2005-11-20 12:21       ` Andy Whitcroft
2005-11-22 18:07       ` [PATCH 0/2] SPARSEMEM: pfn_to_nid implementation v2 Andy Whitcroft
2005-11-22 18:07         ` [PATCH 1/2] flatmem split out memory model Andy Whitcroft
2005-11-22 18:07         ` [PATCH 2/2] sparse provide pfn_to_nid Andy Whitcroft
2005-11-17  0:06   ` [PATCH 0/3] SPARSEMEM: pfn_to_nid implementation Mike Kravetz

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