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Date: Wed, 27 Oct 2004 19:08:16 +0100
From: Christoph Hellwig <hch@infradead.org>
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Cc: Jeff Garzik <jgarzik@pobox.com>,
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Subject: Re: news about IDE PIO HIGHMEM bug (was: Re: 2.6.9-mm1)
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> 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.

I think this is the wrong level of interface exposed.  Just add two hepler
kmap_atomic_sg/kunmap_atomic_sg that gurantee to map/unmap a sg list entry,
even if it's bigger than a page.