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From:   John Stultz <john.stultz@linaro.org>
Date:   Mon, 1 Mar 2021 18:51:09 -0800
Message-ID: <CALAqxLUcbAWiwxqLRmr4Ve4ecSAJ-jsZy-RDC3jqDONgoRht9Q@mail.gmail.com>
Subject: Re: [PATCH] dma-buf: heaps: Set VM_PFNMAP in mmap for system and cma heaps
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Daniel Vetter <daniel@ffwll.ch>,
        lkml <linux-kernel@vger.kernel.org>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Christian Koenig <christian.koenig@amd.com>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Liam Mark <lmark@codeaurora.org>,
        Chris Goldsworthy <cgoldswo@codeaurora.org>,
        Laura Abbott <labbott@kernel.org>,
        Brian Starkey <Brian.Starkey@arm.com>,
        Hridya Valsaraju <hridya@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Sandeep Patil <sspatil@google.com>,
        Daniel Mentz <danielmentz@google.com>,
        "??rjan Eide" <orjan.eide@arm.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Ezequiel Garcia <ezequiel@collabora.com>,
        Simon Ser <contact@emersion.fr>,
        James Jones <jajones@nvidia.com>,
        "open list:DMA BUFFER SHARING FRAMEWORK" 
        <linux-media@vger.kernel.org>,
        dri-devel <dri-devel@lists.freedesktop.org>
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On Sat, Feb 27, 2021 at 1:44 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Fri, Feb 26, 2021 at 08:36:55AM +0100, Daniel Vetter wrote:
> > Also given that both deal with struct page there's a ton of divergence
> > between these two that doesn't make much sense. Maybe could even share
> > the code fully, aside from how you allocate the struct pages.
>
> I've been saying that since the code was first submitted.  Once pages
> are allocated from CMA they should be treated not different from normal
> pages.
>
> Please take a look at how the DMA contigous allocator manages to share
> all code for handling CMA vs alloc_pages pages.

I'll take a look at that! Thanks for the pointer!
-john