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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
Date: Tue, 24 Feb 2015 08:35:48 +0100	[thread overview]
Message-ID: <20150224073548.GB16195@gmail.com> (raw)
In-Reply-To: <1424722477-23758-3-git-send-email-xypron.glpk@gmx.de>


* 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

  parent reply	other threads:[~2015-02-24  7:35 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-17 19:01 [PATCH 1/1 v2] kernel/fork.c: avoid division by zero Heinrich Schuchardt
2015-02-17 23:15 ` Andrew Morton
2015-02-18 19:38   ` Guenter Roeck
2015-02-18 19:50     ` Heinrich Schuchardt
2015-02-18 20:23       ` Guenter Roeck
2015-02-18 19:47   ` Heinrich Schuchardt
2015-02-18 20:28     ` Andrew Morton
2015-02-21 22:19       ` [PATCH 0/3 v3] kernel/fork.c max_thread handling Heinrich Schuchardt
2015-02-21 22:19         ` [PATCH 1/3 v3] kernel/fork.c: avoid division by zero Heinrich Schuchardt
2015-02-22  7:58           ` Ingo Molnar
2015-02-23 20:14             ` [PATCH 0/4 v4] max_threadx handling Heinrich Schuchardt
2015-02-23 20:14               ` [PATCH 1/4 v4] kernel/fork.c: new function for max_threads Heinrich Schuchardt
2015-02-23 20:14               ` [PATCH 2/4 v4] kernel/fork.c: avoid division by zero Heinrich Schuchardt
2015-02-23 21:10                 ` Peter Zijlstra
2015-02-23 21:29                   ` Heinrich Schuchardt
2015-02-24  7:35                 ` Ingo Molnar [this message]
2015-02-23 20:14               ` [PATCH 3/4 v4] kernel/sysctl.c: threads-max observe limits Heinrich Schuchardt
2015-02-23 20:14               ` [PATCH 4/4 v4] kernel/fork.c: memory hotplug updates max_threads Heinrich Schuchardt
2015-02-23 20:50                 ` Oleg Nesterov
2015-02-23 20:54                   ` Oleg Nesterov
2015-02-23 21:11                     ` Heinrich Schuchardt
2015-02-23 21:46                       ` Oleg Nesterov
2015-02-24 19:38               ` [PATCH 0/3 v5] max_threadx handling Heinrich Schuchardt
2015-02-24 19:38                 ` [PATCH 1/3 v5] kernel/fork.c: new function for max_threads Heinrich Schuchardt
2015-02-24 21:03                   ` David Rientjes
2015-02-24 21:23                     ` Heinrich Schuchardt
2015-02-24 22:16                       ` David Rientjes
2015-02-25  7:21                         ` Heinrich Schuchardt
2015-02-25 10:17                         ` Ingo Molnar
2015-02-25 19:08                           ` Heinrich Schuchardt
2015-02-25 21:07                             ` David Rientjes
2015-02-24 19:38                 ` [PATCH 2/3 v5] kernel/fork.c: avoid division by zero Heinrich Schuchardt
2015-02-24 21:14                   ` David Rientjes
2015-02-24 19:38                 ` [PATCH 3/3] kernel/sysctl.c: threads-max observe limits Heinrich Schuchardt
2015-02-24 21:17                   ` David Rientjes
2015-02-24 21:31                     ` Heinrich Schuchardt
2015-02-24 22:20                       ` David Rientjes
2015-02-25 18:47                         ` Heinrich Schuchardt
2015-02-25 20:47                           ` David Rientjes
2015-02-21 22:19         ` [PATCH 2/3 v3] " Heinrich Schuchardt
2015-02-21 22:19         ` [PATCH 3/3 v3] kernel/fork.c: memory hotplug updates max_threads Heinrich Schuchardt

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