diff options
| author | Mel Gorman <mgorman@techsingularity.net> | 2021-12-10 17:00:32 -0800 |
|---|---|---|
| committer | Darrick J. Wong <djwong@kernel.org> | 2021-12-15 17:28:45 -0800 |
| commit | ccb8d6cf4e562ca1e9cceed02fba66eefb76dc97 (patch) | |
| tree | 390a002fc82740029e79d7104ef7fcaf772b51c7 | |
| parent | a4fd547f8cccf65eee6190fb49867013172364dc (diff) | |
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.
This is a fix to the mmotm patch
mm-vmscan-reduce-throttling-due-to-a-failure-to-make-progress.patch
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
| -rw-r--r-- | mm/vmscan.c | 3 |
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 |