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Date: Wed, 15 Jan 2014 02:31:50 -0800
From: Guenter Roeck <linux@roeck-us.net>
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To: Geert Uytterhoeven <geert@linux-m68k.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Michael S. Tsirkin" <mst@redhat.com>
CC: linux-mm@kvack.org, linux-bcache@vger.kernel.org,
        Vineet Gupta <vgupta@synopsys.com>, sparclinux@vger.kernel.org,
        linux-m68k@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: Make {,set}page_address() static inline if WANT_PAGE_VIRTUAL
References: <1389778426-14836-1-git-send-email-geert@linux-m68k.org>
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On 01/15/2014 01:33 AM, Geert Uytterhoeven wrote:
> {,set}page_address() are macros if WANT_PAGE_VIRTUAL.
> If !WANT_PAGE_VIRTUAL, they're plain C functions.
>
> If someone calls them with a void *, this pointer is auto-converted to
> struct page * if !WANT_PAGE_VIRTUAL, but causes a build failure on
> architectures using WANT_PAGE_VIRTUAL (arc, m68k and sparc):
>
> drivers/md/bcache/bset.c: In function ‘__btree_sort’:
> drivers/md/bcache/bset.c:1190: warning: dereferencing ‘void *’ pointer
> drivers/md/bcache/bset.c:1190: error: request for member ‘virtual’ in something not a structure or union
>
> Convert them to static inline functions to fix this. There are already
> plenty of  users of struct page members inside <linux/mm.h>, so there's no
> reason to keep them as macros.
>
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Tested-by: Guenter Roeck <linux@roeck-us.net>

That also fixes the problem seen in stable-queue for 3.10 and 3.12,
so it may be a better fix for the problem seen there than the patch
provided by Michael.

Guenter