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Date: Thu, 23 Jul 2009 16:29:01 -0700 (PDT)
From: David Rientjes <rientjes@google.com>
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To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
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       linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mel@csn.ul.ie,
       npiggin@suse.de
Subject: Re: [PATCH] copy over oom_adj value at fork time
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On Fri, 24 Jul 2009, KOSAKI Motohiro wrote:

> > It's the API that's existed for years with no complaints, AFAICS.
> 
> I think thead and vfork() should be separeted on this discussion.
> I agree vfork() regression should be fixed. but I don't think anyone
> hope per-thread oom score. 
> 
> Of cource, if simple reverting is best way, I don't oppose this.... ;-)
> 

Simply reverting it isn't an option unless you fix the underlying livelock 
problem that my patches originally addressed and no viable alternative has 
been proposed.

On the other hand, I think adding /proc/pid/oom_adj_child would solve the 
userspace issue.  oom_adj_child would be the oom_adj value that is used by 
the newly initialized mm_struct; this would allow the vfork'd child to 
share the same oom_score with the parent and then be replaced with an 
alternate score on execve().

oom_adj_child would only be allowed to be greater (i.e. the more preferred 
victim) than oom_adj for any given thread since the oom killer tries to 
kill a child of the selected task first if it doesn't share memory.