Date: Thu, 21 Apr 2016 16:51:38 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, lftan@altera.com,
        jonas@southpole.se, will.deacon@arm.com
Subject: Re: [PATCH resend 0/3] mm: allow arch to override
 lowmem_page_address
Message-Id: <20160421165138.a57be293ec370d5ea014e1ae@linux-foundation.org>
In-Reply-To: <1460995497-24312-1-git-send-email-ard.biesheuvel@linaro.org>
References: <1460995497-24312-1-git-send-email-ard.biesheuvel@linaro.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1411
Lines: 27

On Mon, 18 Apr 2016 18:04:54 +0200 Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:

> These patches allow the arch to define the page_to_virt() conversion that
> is used in lowmem_page_address(). This is desirable for arm64, where this
> conversion is trivial when CONFIG_SPARSEMEM_VMEMMAP is enabled, while
> breaking it up into __va(PFN_PHYS(page_to_pfn(page))), as is done currently
> in lowmem_page_address(), will force the use of a virt-to-phys() conversion
> and back again, which always involves a memory access on arm64, since the
> start of physical memory is not a compile time constant.
> 
> I have split off these patches from my series 'arm64: optimize virt_to_page
> and page_address' which I sent out 3 weeks ago, and resending them in the
> hope that they can be picked up (with Will's ack on #3) to be merged via
> the mm tree.
> 
> I have cc'ed the nios2 and openrisc maintainers on previous versions, and
> cc'ing them again now. I have dropped both of the arch specific mailing
> lists, since one is defunct and the other is subscriber only.
> 
> Andrew, is this something you would be pulling to pick up (assuming that you
> agree with the contents)? Thanks.

Looks OK to me and apart from the trivial openrisc/nios2 changes it's
obviously a no-op for all-but-arm.  So I suggest you include these
patches in the appropriate arm tree.

Acked-by: Andrew Morton <akpm@linux-foundation.org>