linux-kernel - Re: [PATCH] mm: add config option to select the initial overcommit mode

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Message-ID: <20160513160142.2cc7d695@lxorguk.ukuu.org.uk>
Date:	Fri, 13 May 2016 16:01:42 +0100
From:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
To:	Sebastian Frias <sf84@...oste.net>
Cc:	"Austin S. Hemmelgarn" <ahferroin7@...il.com>,
	Michal Hocko <mhocko@...nel.org>, Mason <slash.tmp@...e.fr>,
	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: add config option to select the initial overcommit
 mode

On Fri, 13 May 2016 15:34:52 +0200
Sebastian Frias <sf84@...oste.net> wrote:

> Hi Austin,
> 
> On 05/13/2016 03:11 PM, Austin S. Hemmelgarn wrote:
> > On 2016-05-13 08:39, Sebastian Frias wrote:  
> >>
> >> My point is that it seems to be possible to deal with such conditions in a more controlled way, ie: a way that is less random and less abrupt.  
> > There's an option for the OOM-killer to just kill the allocating task instead of using the scoring heuristic.  This is about as deterministic as things can get though.  
> 
> By the way, why does it has to "kill" anything in that case?
> I mean, shouldn't it just tell the allocating task that there's not enough memory by letting malloc return NULL?

Just turn off overcommit and it will do that. With overcommit disabled
the kernel will not hand out address space in excess of memory plus swap.

Alan