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

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Message-ID: <5735F4B1.1010704@laposte.net>
Date:	Fri, 13 May 2016 17:37:21 +0200
From:	Sebastian Frias <sf84@...oste.net>
To:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Michal Hocko <mhocko@...nel.org>
CC:	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

Hi Alan,

On 05/13/2016 05:04 PM, One Thousand Gnomes wrote:
>>> Perhaps Sebastian's choice could be made to depend on CONFIG_EMBEDDED,
>>> rather than CONFIG_EXPERT?  
>>
>> Even if the overcommit behavior is different on those systems the
>> primary question hasn't been answered yet. Why cannot this be done from
>> the userspace? In other words what wouldn't work properly?
> 
> Most allocations in C have no mechanism to report failure.
> 
> Stakc expansion failure is not reportable. Copy on write failure is not
> reportable and so on.

But wouldn't those affect a given process at at time?
Does that means that the OOM-killer is woken up to kill process X when those situations arise on process Y?

Also, under what conditions would copy-on-write fail?

Best regards,

Sebastian