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Date: Tue, 24 Apr 2018 23:59:30 -0700
From: Christoph Hellwig <hch@infradead.org>
To: David Rientjes <rientjes@google.com>
Cc: Christoph Hellwig <hch@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [GIT PULL] dma mapping fixes for 4.17-rc3
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On Tue, Apr 24, 2018 at 11:54:26PM -0700, David Rientjes wrote:
> Shouldn't that test for dev->coherent_dma_mask < DMA_BIT_MASK(32) be more 
> accurately <=? 

No, it should really be <.  The exactly 32-bit case is already covered
with GFP_DMA32.  Eventualy it should be < 24-bit with a separate
GFP_DMA32 case for > 32-bit && < 64-bit.  Takashi has been working on
that, but it is 4.18 material.