linux-kernel - Re: Regression due to d98849aff879 (dma-direct: handle DMA_ATTR_NO_KERNEL

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Date:   Tue, 6 Aug 2019 17:46:02 +0200
From:   Christoph Hellwig <hch@....de>
To:     "Lendacky, Thomas" <Thomas.Lendacky@....com>
Cc:     Lucas Stach <l.stach@...gutronix.de>,
        Christoph Hellwig <hch@....de>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Halil Pasic <pasic@...ux.ibm.com>
Subject: Re: Regression due to d98849aff879 (dma-direct: handle
 DMA_ATTR_NO_KERNEL_MAPPING in common code)

On Tue, Aug 06, 2019 at 02:18:49PM +0000, Lendacky, Thomas wrote:
> I think you need to keep everything inside the original if statement since
> the caller is expecting a page pointer to be returned in this case and not
> the page_address() which is returned when the DMA_ATTR_NO_KERNEL_MAPPING
> is not present.

DMA_ATTR_NO_KERNEL_MAPPING is defined to return an opaque cookie,
which just happens to be a page pointer.  So if we fix up the free side
as pointed out by Lucas we should be fine.