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Date:   Fri, 14 Jun 2019 17:05:58 +0200
From:   'Christoph Hellwig' <hch@lst.de>
To:     David Laight <David.Laight@ACULAB.COM>
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Subject: Re: [PATCH 16/16] dma-mapping: use exact allocation in
 dma_alloc_contiguous
Message-ID: <20190614150558.GA9402@lst.de>
References: <20190614134726.3827-1-hch@lst.de> <20190614134726.3827-17-hch@lst.de> <a90cf7ec5f1c4166b53c40e06d4d832a@AcuMS.aculab.com> <20190614145001.GB9088@lst.de> <d93fd4c2c1584d92a05dd641929f6d63@AcuMS.aculab.com>
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On Fri, Jun 14, 2019 at 03:01:22PM +0000, David Laight wrote:
> I'm pretty sure there is a lot of code out there that makes that assumption.
> Without it many drivers will have to allocate almost double the
> amount of memory they actually need in order to get the required alignment.
> So instead of saving memory you'll actually make more be used.

That code would already be broken on a lot of Linux platforms.