From: "Martin J. Bligh" <mbligh@aracnet.com>
To: Jeff Garzik <jgarzik@pobox.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>,
"Randy.Dunlap" <rddunlap@osdl.org>,
William Lee Irwin III <wli@holomorphy.com>,
Jens Axboe <axboe@suse.de>
Subject: Re: news about IDE PIO HIGHMEM bug (was: Re: 2.6.9-mm1)
Date: Wed, 27 Oct 2004 09:01:24 -0700 [thread overview]
Message-ID: <1246750000.1098892883@[10.10.2.4]> (raw)
In-Reply-To: <1246230000.1098892359@[10.10.2.4]>
--"Martin J. Bligh" <mbligh@aracnet.com> wrote (on Wednesday, October 27, 2004 08:52:39 -0700):
>> Bartlomiej Zolnierkiewicz wrote:
>>> We have stuct page of the first page and a offset.
>>> We need to obtain struct page of the current page and map it.
>>
>>
>> Opening this question to a wider audience.
>>
>> struct scatterlist gives us struct page*, and an offset+length pair. The struct page* is the _starting_ page of a potentially multi-page run of data.
>>
>> The question: how does one get struct page* for the second, and successive pages in a known-contiguous multi-page run, if one only knows the first page?
>
> If it's a higher order allocation, just page+1 should be safe. If it just
> happens to be contig, it might cross a discontig boundary, and not obey
> that rule. Very unlikely, but possible.
To repeat what I said in IRC ... ;-)
Actually, you could check this with the pfns being the same when >> MAX_ORDER-1.
We should be aligned on a MAX_ORDER boundary, I think.
However, pfn_to_page(page_to_pfn(page) + 1) might be safer. If rather slower.
M.
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next prev parent reply other threads:[~2004-10-27 16:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <58cb370e041027074676750027@mail.gmail.com>
2004-10-27 15:14 ` Jeff Garzik
2004-10-27 15:52 ` Martin J. Bligh
2004-10-27 15:59 ` Jeff Garzik
2004-10-27 17:36 ` Martin J. Bligh
2004-10-27 16:01 ` Martin J. Bligh [this message]
2004-10-27 16:35 ` [PATCH] " Jeff Garzik
2004-10-27 21:29 ` Andrew Morton
2004-10-27 21:31 ` Jeff Garzik
2004-10-27 21:34 ` William Lee Irwin III
2004-10-27 18:08 ` Christoph Hellwig
2004-10-27 18:33 ` news about IDE PIO HIGHMEM bug Jeff Garzik
2004-10-27 18:48 ` William Lee Irwin III
2004-10-28 0:18 ` William Lee Irwin III
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