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From: Andries Brouwer <Andries.Brouwer@cwi.nl>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Andries.Brouwer@cwi.nl, akpm@osdl.org, torvalds@osdl.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] overcommit symbolic constants
Date: Thu, 30 Sep 2004 16:19:05 +0200	[thread overview]
Message-ID: <20040930141905.GA4077@apps.cwi.nl> (raw)
In-Reply-To: <1096548791.19269.5.camel@localhost.localdomain>

On Thu, Sep 30, 2004 at 01:53:12PM +0100, Alan Cox wrote:
> On Iau, 2004-09-30 at 14:41, Andries.Brouwer@cwi.nl wrote:
> > Played a bit with overcommit the past hour.
> > Am not entirely satisfied with the no overcommit mode 2 -
> > programs segfault when the system is close to that boundary.
> 
> Not really a suprise. Very few programs handle stack growth faults.
> Hence the docs comment about mmapping stacks privately for critical
> code.

Most utilities do not expect to be oom-killed, but they do not
expect to be killed by segfault because of stack shortage either.
So avoiding the oom-kill and getting segfaults is no improvement
in my eyes.

A few days ago I remarked that 2 is no good when there is no swap.
OK. So, more modest aim - tighten things only in case there is
plenty of swap. I like to return NULL for malloc(), that is
something a good program tests for. I hate to fail a stack grow.
So, must play a bit more, see whether I can find a mode much
stricter than 0 that is still suitable as a general working
environment for everybody.


Andries



  reply	other threads:[~2004-09-30 14:19 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-09-30 13:41 [PATCH] overcommit symbolic constants Andries.Brouwer
2004-09-30 12:53 ` Alan Cox
2004-09-30 14:19   ` Andries Brouwer [this message]
2004-09-30 13:27     ` Alan Cox
2004-09-30 20:26       ` Andries Brouwer
2004-09-30 14:25 ` Hugh Dickins

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