From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH 1/2] vmscan: consider classzone_idx in compaction_ready
Date: Mon, 11 Apr 2016 17:24:42 +0200 [thread overview]
Message-ID: <570BC1BA.6070904@suse.cz> (raw)
In-Reply-To: <1460357151-25554-2-git-send-email-mhocko@kernel.org>
On 04/11/2016 08:45 AM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> while playing with the oom detection rework [1] I have noticed
> that my heavy order-9 (hugetlb) load close to OOM ended up in an
> endless loop where the reclaim hasn't made any progress but
> did_some_progress didn't reflect that and compaction_suitable
> was backing off because no zone is above low wmark + 1 << order.
>
> It turned out that this is in fact an old standing bug in compaction_ready
> which ignores the requested_highidx and did the watermark check for
> 0 classzone_idx. This succeeds for zone DMA most of the time as the zone
> is mostly unused because of lowmem protection. This also means that the
> OOM killer wouldn't be triggered for higher order requests even when
> there is no reclaim progress and we essentially rely on order-0 request
> to find this out. This has been broken in one way or another since
> fe4b1b244bdb ("mm: vmscan: when reclaiming for compaction, ensure there
> are sufficient free pages available") but only since 7335084d446b ("mm:
> vmscan: do not OOM if aborting reclaim to start compaction") we are not
> invoking the OOM killer based on the wrong calculation.
>
> Propagate requested_highidx down to compaction_ready and use it for both
> the watermak check and compaction_suitable to fix this issue.
>
> [1] http://lkml.kernel.org/r/1459855533-4600-1-git-send-email-mhocko@kernel.org
> Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
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next prev parent reply other threads:[~2016-04-11 15:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-11 6:45 [PATCH 0/2] oom detection rework followups Michal Hocko
2016-04-11 6:45 ` [PATCH 1/2] vmscan: consider classzone_idx in compaction_ready Michal Hocko
2016-04-11 15:24 ` Vlastimil Babka [this message]
2016-04-11 6:45 ` [PATCH 2/2] mm, oom, compaction: prevent from should_compact_retry looping for ever for costly orders Michal Hocko
2016-04-12 7:23 ` Vlastimil Babka
2016-04-12 12:43 ` Michal Hocko
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