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authorMel Gorman <mgorman@techsingularity.net>2021-12-31 22:10:09 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2021-12-31 22:12:55 +0100
commit8008293888188c3923f5bd8a69370dae25ed14e5 (patch)
tree4ddefd2eb46ae893bbf9a58fcf4b1b1747e80c65 /mm/vmscan.c
parentmm: vmscan: Reduce throttling due to a failure to make progress (diff)
downloadlinux-8008293888188c3923f5bd8a69370dae25ed14e5.tar.xz
linux-8008293888188c3923f5bd8a69370dae25ed14e5.zip
mm: vmscan: reduce throttling due to a failure to make progress -fix
Hugh Dickins reported the following 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); The likely issue is that huge pages are a major component of the test workload. When this is the case, first_pgdat may never get set if compaction is ready to continue due to this check if (IS_ENABLED(CONFIG_COMPACTION) && sc->order > PAGE_ALLOC_COSTLY_ORDER && compaction_ready(zone, sc)) { sc->compaction_ready = true; continue; } If this was true for every zone in the zonelist, first_pgdat would never get set resulting in a NULL pointer exception. Link: https://lkml.kernel.org/r/20211209095453.GM3366@techsingularity.net Fixes: 1b4e3f26f9f75 ("mm: vmscan: Reduce throttling due to a failure to make progress") Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reported-by: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Rik van Riel <riel@surriel.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4c4d5f6cd8a3..700434db5735 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3530,7 +3530,8 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
shrink_node(zone->zone_pgdat, sc);
}
- consider_reclaim_throttle(first_pgdat, sc);
+ if (first_pgdat)
+ consider_reclaim_throttle(first_pgdat, sc);
/*
* Restore to original mask to avoid the impact on the caller if we