linux-kernel - Re: [PATCH] mm, vmscan: do not loop on too_many

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Date:   Thu, 09 Mar 2017 09:16:25 -0500
From:   Rik van Riel <riel@...hat.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...e.de>,
        Johannes Weiner <hannes@...xchg.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm, vmscan: do not loop on too_many_isolated for ever

On Thu, 2017-03-09 at 10:12 +0100, Michal Hocko wrote:
> On Wed 08-03-17 10:54:57, Rik van Riel wrote:

> > In fact, false OOM kills with that kind of workload is
> > how we ended up getting the "too many isolated" logic
> > in the first place.
> Right, but the retry logic was considerably different than what we
> have these days. should_reclaim_retry considers amount of reclaimable
> memory. As I've said earlier if we see a report where the oom hits
> prematurely with many NR_ISOLATED* we know how to fix that.

Would it be enough to simply reset no_progress_loops
in this check inside should_reclaim_retry, if we know
pageout IO is pending?

                        if (!did_some_progress) {
                                unsigned long write_pending;

                                write_pending =
zone_page_state_snapshot(zone,
                                                        NR_ZONE_WRITE_P
ENDING);

                                if (2 * write_pending > reclaimable) {
                                        congestion_wait(BLK_RW_ASYNC,
HZ/10);
                                        return true;
                                }
                        }

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