Date: Thu, 11 Dec 2008 20:28:00 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Yuri Tikhonov <yur@emcraft.com>, linux-kernel@vger.kernel.org,
       linuxppc-dev@ozlabs.org, Geert.Uytterhoeven@sonycom.com,
       dhowells@redhat.com, miltonm@bga.com, wd@denx.de, dzu@denx.de,
       yanok@emcraft.com
Subject: Re: [PATCH][v2] fork_init: fix division by zero
Message-ID: <20081211202800.GQ28946@ZenIV.linux.org.uk>
References: <200812101950.51958.yur@emcraft.com> <20081211121635.ff58193f.akpm@linux-foundation.org>
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On Thu, Dec 11, 2008 at 12:16:35PM -0800, Andrew Morton wrote:
> > +#if (8 * THREAD_SIZE) > PAGE_SIZE
> >  	max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
> > +#else
> > +	max_threads = mempages * (PAGE_SIZE / (8 * THREAD_SIZE));
> > +#endif
> 
> The expression you've chosen here can be quite inacccurate, because
> ((PAGE_SIZE / (8 * THREAD_SIZE)) is a small number.  The way to
> preserve accuracy is
> 
> 	max_threads = (mempages * PAGE_SIZE) / (8 * THREAD_SIZE);
> 
> so how about avoiding the nasty ifdefs and doing

Are you sure?  Do they actually cross the page boundaries?
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