From: Mel Gorman <mgorman@techsingularity.net>
To: Alexey Avramov <hakavlad@inbox.lv>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
mhocko@suse.com, vbabka@suse.cz, neilb@suse.de,
akpm@linux-foundation.org, corbet@lwn.net, riel@surriel.com,
hannes@cmpxchg.org, david@fromorbit.com, willy@infradead.org,
hdanton@sina.com, penguin-kernel@i-love.sakura.ne.jp,
oleksandr@natalenko.name, kernel@xanmod.org,
michael@michaellarabel.com, aros@gmx.com, hakavlad@gmail.com
Subject: Re: mm: 5.16 regression: reclaim_throttle leads to stall in near-OOM conditions
Date: Wed, 24 Nov 2021 11:50:07 +0000 [thread overview]
Message-ID: <20211124115007.GG3366@techsingularity.net> (raw)
In-Reply-To: <20211124195449.33f31e7f@mail.inbox.lv>
On Wed, Nov 24, 2021 at 07:54:49PM +0900, Alexey Avramov wrote:
> > it does eventually get killed OOM
>
> However, a full minute freeze can be a great evil in many situations -
> during such a freeze, the system is completely unresponsive.
>
> So my next question is: How reasonable is the value MAX_RECLAIM_RETRIES?
> Is it also get "out of thin air"?
>
The value is out of thin air but adjusting it may reintroduce issues
with kswapd running at 100% CPU.
> And would it make sense to have buttons to adjust the timeouts?
I don't think we should introduce a tunable for something like this,
it'll be impossible to use properly but can you test this?
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 07db03883062..aa72c0f39dcc 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1058,6 +1058,14 @@ void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason)
break;
case VMSCAN_THROTTLE_NOPROGRESS:
timeout = HZ/2;
+
+ /*
+ * If kswapd is disabled, use the minimum timeout as the
+ * system may be at or near OOM.
+ */
+ if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES)
+ timeout = 1;
+
break;
case VMSCAN_THROTTLE_ISOLATED:
timeout = HZ/50;
@@ -3395,7 +3403,7 @@ static void consider_reclaim_throttle(pg_data_t *pgdat, struct scan_control *sc)
return;
/* Throttle if making no progress at high prioities. */
- if (sc->priority < DEF_PRIORITY - 2)
+ if (sc->priority < DEF_PRIORITY - 2 && !sc->nr_reclaimed)
reclaim_throttle(pgdat, VMSCAN_THROTTLE_NOPROGRESS);
}
@@ -3415,6 +3423,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
unsigned long nr_soft_scanned;
gfp_t orig_mask;
pg_data_t *last_pgdat = NULL;
+ pg_data_t *first_pgdat = NULL;
/*
* If the number of buffer_heads in the machine exceeds the maximum
@@ -3478,14 +3487,18 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
/* need some check for avoid more shrink_zone() */
}
+ if (!first_pgdat)
+ first_pgdat = zone->zone_pgdat;
+
/* See comment about same check for global reclaim above */
if (zone->zone_pgdat == last_pgdat)
continue;
last_pgdat = zone->zone_pgdat;
shrink_node(zone->zone_pgdat, sc);
- consider_reclaim_throttle(zone->zone_pgdat, sc);
}
+ consider_reclaim_throttle(first_pgdat, sc);
+
/*
* Restore to original mask to avoid the impact on the caller if we
* promoted it to __GFP_HIGHMEM.
next prev parent reply other threads:[~2021-11-24 11:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-23 16:19 mm: 5.16 regression: reclaim_throttle leads to stall in near-OOM conditions Alexey Avramov
2021-11-24 7:40 ` Thorsten Leemhuis
2021-11-24 10:35 ` Mel Gorman
2021-11-24 10:54 ` Alexey Avramov
2021-11-24 11:50 ` Mel Gorman [this message]
2021-11-24 12:03 ` Alexey Avramov
2021-11-24 12:44 ` Alexey Avramov
2021-11-24 14:33 ` Mel Gorman
2021-11-26 16:06 ` Alexey Avramov
2021-11-26 16:24 ` Mel Gorman
2021-12-20 8:50 ` Sultan Alsawaf
2021-11-27 19:37 ` Alexey Avramov
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