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Re: [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM

From Michal Hocko <mhocko@kernel.org>
Newsgroups linux.kernel
Subject Re: [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM
Date 2016-10-11 10:10 +0200
Message-ID <sr0il-49R-5@gated-at.bofh.it> (permalink)
References (5 earlier) <sqXu9-2rb-11@gated-at.bofh.it> <sqZcC-3iR-23@gated-at.bofh.it> <sqZFD-3Hq-1@gated-at.bofh.it> <sqZFE-3Hq-11@gated-at.bofh.it> <sqZPj-3Ko-5@gated-at.bofh.it>
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On Tue 11-10-16 16:37:16, Minchan Kim wrote:
> On Tue, Oct 11, 2016 at 09:26:06AM +0200, Michal Hocko wrote:
> > On Tue 11-10-16 16:09:45, Minchan Kim wrote:
[...]
> > > @@ -2154,12 +2156,24 @@ static void unreserve_highatomic_pageblock(const struct alloc_context *ac)
> > >  			 * may increase.
> > >  			 */
> > >  			set_pageblock_migratetype(page, ac->migratetype);
> > > -			move_freepages_block(zone, page, ac->migratetype);
> > > -			spin_unlock_irqrestore(&zone->lock, flags);
> > > -			return;
> > > +			ret = move_freepages_block(zone, page,
> > > +						ac->migratetype);
> > > +			/*
> > > +			 * By race with page freeing functions, !highatomic
> > > +			 * pageblocks can have free pages in highatomic free
> > > +			 * list so if drain is true, try to unreserve every
> > > +			 * free pages in highatomic free list without bailing
> > > +			 * out.
> > > +			 */
> > > +			if (!drain) {
> > 
> > 			if (ret)
> > > +				spin_unlock_irqrestore(&zone->lock, flags);
> > > +				return ret;
> > > +			}
> > 
> > arguably this would work better also for !drain case which currently
> > tries to unreserve but in case of the race it would do nothing.
> 
> I thought it but I was afraid if you say again it's over complicated.

Well, maybe there is even better/easier solution. Anyway, if
I were you I would just split it into two patches. The first
to unreserve from shoudl_reclaim_retry and the later to make
unreserve_highatomic_pageblock more reliable.

> I will do it with your SOB in next spin.

ok, thanks!
-- 
Michal Hocko
SUSE Labs

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Thread

[PATCH 0/4] use up highorder free pages before OOM Minchan Kim <minchan@kernel.org> - 2016-10-07 07:50 +0200
  [PATCH 4/4] mm: skip to reserve pageblock crossed zone boundary for HIGHATOMIC Minchan Kim <minchan@kernel.org> - 2016-10-07 07:50 +0200
  [PATCH 1/4] mm: adjust reserved highatomic count Minchan Kim <minchan@kernel.org> - 2016-10-07 07:50 +0200
    Re: [PATCH 1/4] mm: adjust reserved highatomic count Vlastimil Babka <vbabka@suse.cz> - 2016-10-07 14:40 +0200
      Re: [PATCH 1/4] mm: adjust reserved highatomic count Minchan Kim <minchan@kernel.org> - 2016-10-07 16:30 +0200
        Re: [PATCH 1/4] mm: adjust reserved highatomic count Vlastimil Babka <vbabka@suse.cz> - 2016-10-10 09:40 +0200
          Re: [PATCH 1/4] mm: adjust reserved highatomic count Minchan Kim <minchan@kernel.org> - 2016-10-11 06:40 +0200
            Re: [PATCH 1/4] mm: adjust reserved highatomic count Vlastimil Babka <vbabka@suse.cz> - 2016-10-11 12:00 +0200
            Re: [PATCH 1/4] mm: adjust reserved highatomic count Mel Gorman <mgorman@techsingularity.net> - 2016-10-12 07:50 +0200
  [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Minchan Kim <minchan@kernel.org> - 2016-10-07 07:50 +0200
    Re: [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Michal Hocko <mhocko@kernel.org> - 2016-10-07 11:10 +0200
      Re: [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Minchan Kim <minchan@kernel.org> - 2016-10-07 16:50 +0200
        Re: [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Michal Hocko <mhocko@kernel.org> - 2016-10-10 09:50 +0200
          Re: [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Minchan Kim <minchan@kernel.org> - 2016-10-11 07:10 +0200
            Re: [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Michal Hocko <mhocko@kernel.org> - 2016-10-11 09:00 +0200
              Re: [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Minchan Kim <minchan@kernel.org> - 2016-10-11 09:30 +0200
                Re: [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Michal Hocko <mhocko@kernel.org> - 2016-10-11 09:30 +0200
                Re: [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Minchan Kim <minchan@kernel.org> - 2016-10-11 09:40 +0200
                Re: [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Michal Hocko <mhocko@kernel.org> - 2016-10-11 10:10 +0200
  Re: [PATCH 0/4] use up highorder free pages before OOM Michal Hocko <mhocko@kernel.org> - 2016-10-07 11:20 +0200
    Re: [PATCH 0/4] use up highorder free pages before OOM Minchan Kim <minchan@kernel.org> - 2016-10-07 17:50 +0200
      Re: [PATCH 0/4] use up highorder free pages before OOM Michal Hocko <mhocko@kernel.org> - 2016-10-10 10:00 +0200
        Re: [PATCH 0/4] use up highorder free pages before OOM Minchan Kim <minchan@kernel.org> - 2016-10-11 07:10 +0200
          Re: [PATCH 0/4] use up highorder free pages before OOM Michal Hocko <mhocko@kernel.org> - 2016-10-11 09:00 +0200

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