To: Christoph Hellwig <hch@lst.de>
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From: Logan Gunthorpe <logang@deltatee.com>
Message-ID: <3b7f3aba-d609-dca7-149f-107757d63fb0@deltatee.com>
Date: Thu, 27 Apr 2017 09:44:18 -0600
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On 27/04/17 12:53 AM, Christoph Hellwig wrote:
> I think you'll need to follow the existing kmap semantics and never
> fail the iomem version either.  Otherwise you'll have a special case
> that's almost never used that has a different error path.
>
> Again, wrong way.  Suddenly making things fail for your special case
> that normally don't fail is a receipe for bugs.

I don't disagree but these restrictions make the problem impossible to
solve? If there is iomem behind a page in an SGL and someone tries to
map it, we either have to fail or we break iomem safety which was your
original concern.

Logan