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Date: Mon, 17 Oct 2011 15:34:29 -0700 (PDT)
From: Hugh Dickins <hughd@google.com>
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To: Alan Cox <alan@lxorguk.ukuu.org.uk>
cc: Rob Clark <rob.clark@linaro.org>,
        Patrik Jakobsson <patrik.r.jakobsson@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Hellwig <hch@infradead.org>, greg@kroah.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 34/49] gma500: the GEM and GTT code is device
 independant
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On Mon, 17 Oct 2011, Alan Cox wrote:
> > It feels to me like GEM is pulling shmem in an ever more alien direction:
> > these device constraints are so foreign to the nature of tmpfs; and
> > beyond my expertise, so that I'd be ever more likely to make the wrong
> > decisions (mixing swap and uncached pages? hmmm).
> 
> For the most part we fixed that. You can now have a GEM object that is
> backed by a private memory object rather than having to be tmpfs.
> GMA500 uses it to attach 'stolen' memory to GEM handles, and at least
> one other pending submission uses it with a private CMA style allocator.

Sounds good.
> 
> The gma500 report seems an odd one - no GMA500 box has >4GB memory so how
> did the test code get a page that was unsuitable - is the test buggy ?

This is the first I heard of some gma500 test seeing a problem with >4GB.

In this thread we have Patrik hitting the oops in read_cache_page_gfp()
because of some changes he is preparing, but I thought he and Rob were
just thinking ahead when they raise the 4GB issue.

Can you point us to another thread on a another list?

Hugh