Date: Tue, 24 Feb 2015 08:35:48 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Aaron Tomlin <atomlin@redhat.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Davidlohr Bueso <dave@stgolabs.net>,
        David Rientjes <rientjes@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Fabian Frederick <fabf@skynet.be>, Guenter Roeck <linux@roeck-us.net>,
        "H. Peter Anvin" <hpa@zytor.com>, Jens Axboe <axboe@fb.com>,
        Joe Perches <joe@perches.com>, Johannes Weiner <hannes@cmpxchg.org>,
        Kees Cook <keescook@chromium.org>,
        Michael Marineau <mike@marineau.org>, Oleg Nesterov <oleg@redhat.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Prarit Bhargava <prarit@redhat.com>, Rik van Riel <riel@redhat.com>,
        Rusty Russell <rusty@rustcorp.com.au>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vladimir Davydov <vdavydov@parallels.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4 v4] kernel/fork.c: avoid division by zero
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* Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:

> PAGE_SIZE is not guaranteed to be equal to or less than 8 times the
> THREAD_SIZE.
> 
> E.g. architecture hexagon may have page size 1M and thread size 4096.
> This would lead to a division by zero in the calculation of max_threads.
> 
> With 32-bit calculus there is no solution which delivers valid results
> for all possible combinations of the parameters.
> The code is only called once.
> Hence a 64-bit calculation can be used as solution.
> 
> The calculation of max_threads is moved to a separate function.

Please keep the 'move to a separate function' patch in a 
separate patch and don't mix it up with the fix, as I 
suggested it in my previous review.

Thanks,

	Ingo
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