From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: [RFC][PATCH] introduce ptr_diff()
Date: Fri, 20 Aug 2010 13:12:39 +0100
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To: Andi Kleen <andi@firstfloor.org>
Cc: Bernd Petrovitsch <bernd@sysprog.at>, Namhyung Kim <namhyung@gmail.com>, Arnd Bergmann <arnd@arndb.de>, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org

On Thu, Aug 19, 2010 at 02:59:57PM +0200, Andi Kleen wrote:
> > If so, the warning seems valid as sizeof(struct page) is probably not
> > (always) a power of 2. On a native build on x86_64 it is 56 bytes
> > hereover.
> > Hmm ....
> 
> 
> gcc just generats a mull with inverted value. mull is cheap on any
> reasonable CPU.

Depends on gcc version.

> Please fix sparse.

Frankly, I'd rather stop crapping -Wall into its arguments; there's
a reason why that check is optional and it's *not* defaulting to
on in sparse.