linux-kernel - Re: [patch] mm, oom: remove gfp helper function

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Message-ID: <20141201233040.GB29642@phnom.home.cmpxchg.org>
Date:	Mon, 1 Dec 2014 18:30:40 -0500
From:	Johannes Weiner <hannes@...xchg.org>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	David Rientjes <rientjes@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Qiang Huang <h.huangqiang@...wei.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [patch] mm, oom: remove gfp helper function

On Thu, Nov 27, 2014 at 11:25:47AM +0100, Michal Hocko wrote:
> On Wed 26-11-14 14:17:32, David Rientjes wrote:
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -2706,7 +2706,7 @@ rebalance:
> >  	 * running out of options and have to consider going OOM
> >  	 */
> >  	if (!did_some_progress) {
> > -		if (oom_gfp_allowed(gfp_mask)) {
> 		/*
> 		 * Do not attempt to trigger OOM killer for !__GFP_FS
> 		 * allocations because it would be premature to kill
> 		 * anything just because the reclaim is stuck on
> 		 * dirty/writeback pages.
> 		 * __GFP_NORETRY allocations might fail and so the OOM
> 		 * would be more harmful than useful.
> 		 */

I don't think we need to explain the individual flags, but it would
indeed be useful to remark here that we shouldn't OOM kill from
allocations contexts with (severely) limited reclaim abilities.
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