Re: [PATCH v4 1/1] mm: vmscan: Reduce throttling due to a failure to make progress
From: Hugh Dickins <hughd@google.com>
Date: 2021-12-09 06:20:55
Also in:
linux-fsdevel, lkml, regressions
On Thu, 2 Dec 2021, Mel Gorman wrote: ...
quoted hunk ↗ jump to hunk
--- a/mm/vmscan.c +++ b/mm/vmscan.c
...
quoted hunk ↗ jump to hunk
@@ -3478,14 +3520,18 @@ 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);
My tmpfs swapping load (tweaked to use huge pages more heavily than in real life) is far from being a realistic load: but it was notably slowed down by your throttling mods in 5.16-rc, and this patch makes it well again - thanks. But: it very quickly hit NULL pointer until I changed that last line to if (first_pgdat) consider_reclaim_throttle(first_pgdat, sc); I've given no thought as to whether that is the correct fix, or if first_pgdat should be set earlier in the loop above. Hugh