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Date: Fri, 26 Feb 2016 10:24:07 +0100
From: Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH 0/3] OOM detection rework v4
Message-ID: <20160226092406.GB8940@dhcp22.suse.cz>
References: <1450203586-10959-1-git-send-email-mhocko@kernel.org>
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 <alpine.LSU.2.11.1602241832160.15564@eggly.anvils>
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To: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: 'Hugh Dickins' <hughd@google.com>, 'Andrew Morton' <akpm@linux-foundation.org>, 'Linus Torvalds' <torvalds@linux-foundation.org>, 'Johannes Weiner' <hannes@cmpxchg.org>, 'Mel Gorman' <mgorman@suse.de>, 'David Rientjes' <rientjes@google.com>, 'Tetsuo Handa' <penguin-kernel@i-love.sakura.ne.jp>, 'KAMEZAWA Hiroyuki' <kamezawa.hiroyu@jp.fujitsu.com>, linux-mm@kvack.org, 'LKML' <linux-kernel@vger.kernel.org>, 'Sergey Senozhatsky' <sergey.senozhatsky.work@gmail.com>

On Fri 26-02-16 15:54:19, Hillf Danton wrote:
> > 
> > It didn't really help, I'm afraid: it reduces the actual number of OOM
> > kills which occur before the job is terminated, but doesn't stop the
> > job from being terminated very soon.
> > 
> > I also tried Hillf's patch (separately) too, but as you expected,
> > it didn't seem to make any difference.
> > 
> Perhaps non-costly means NOFAIL as shown by folding the two

nofail only means that the page allocator doesn't return with NULL.
OOM killer is still not put aside...

> patches into one. Can it make any sense?
> 
> thanks
> Hillf
> --- a/mm/page_alloc.c	Thu Feb 25 15:43:18 2016
> +++ b/mm/page_alloc.c	Fri Feb 26 15:18:55 2016
> @@ -3113,6 +3113,8 @@ should_reclaim_retry(gfp_t gfp_mask, uns
>  	struct zone *zone;
>  	struct zoneref *z;
>  
> +	if (order <= PAGE_ALLOC_COSTLY_ORDER)
> +		return true;

This is defeating the whole purpose of the rework - to behave
deterministically. You have just disabled the oom killer completely.
This is not the way to go

-- 
Michal Hocko
SUSE Labs

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