Date: Sun, 18 Sep 2005 21:22:12 +1000
From: Anton Blanchard <anton@samba.org>
To: "Sexton, Matt" <sexton@mc.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: inconsistent mmap and get_user_pages with hugetlbfs on ppc64
Message-ID: <20050918112212.GD17639@krispykreme>
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Hi,

> On a ppc64 platform running 2.6.13-1, the virtual to physical mapping
> established by mmap'ing a hugetlbfs file does not seem to match the
> mapping described by get_user_pages().

I just tried a simple test - I created a program that allocated a
hugetlb page and wrote some stuff in it. I then attached with gdb and
dumped memory at that address and things came out OK.

That should have exercised the ptrace -> access_process_vm -> get_user_pages
path. So at least for this case get_user_pages seems to be working :)

It would be useful to simplify your problem a bit and take DMA out of
the picture. Moving this over to linuxppc64-dev@ozlabs.org would also
make sense.

Anton
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