linux-kernel - Re: 答复: [PATCHv2 4.3-rc6] proc: fix convert from oom_score_adj to oom

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Date:	Sat, 31 Oct 2015 21:30:15 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
cc:	Hongjie Fang (方洪杰) 
	<Hongjie.Fang@...eadtrum.com>, Michal Hocko <mhocko@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: 答复: [PATCHv2 4.3-rc6] proc: fix convert from oom_score_adj to oom_adj

On Wed, 28 Oct 2015, Eric W. Biederman wrote:

> > It's confusing, but with purpose: it shows there is no direct mapping 
> > between /proc/pid/oom_adj and /proc/pid/oom_score_adj.  
> > /proc/pid/oom_score_adj is the effective policy and has been for years.  
> > The value returned by /proc/pid/oom_adj demonstrates reality vs what is 
> > perceived and is a side-effect of integer division truncating the result 
> > in C.
> >
> > It's a bad situation, I agree, and we anticipated the complete removal of 
> > /proc/pid/oom_adj years ago since it has been deprecated for years.  Maybe 
> > one day we can convince Linus that is possible, but until then we're stuck 
> > with it.
> 
> If you really want to remove /proc/pid/oom_adj start by placing it in a
> Kconfig so people can make it go away.
> 

[+akpm]

We've tried to remove it over the period of a couple of years after 
oom_score_adj was introduced.  I believe we had a WARN_ON() for the first 
two years and then removed it all together.  A few months later, there was 
a bug report because the file didn't exist and Linus insisted it be 
readded because we don't break userspace.

I would absolutely love to remove oom_adj, but I'm afraid that it may not 
be possible.
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