cb731d6 ("vmscan: per memory cgroup slab shrinkers") sought to
optimize accumulating slab reclaim results in sc->nr_reclaimed only
once per zone, but the memcg hierarchy walk itself uses
sc->nr_reclaimed as an exit condition. This can lead to overreclaim.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
mm/vmscan.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 27d580b..a02654e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2441,11 +2441,18 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc,
shrink_lruvec(lruvec, swappiness, sc, &lru_pages);
zone_lru_pages += lru_pages;
- if (memcg && is_classzone)
+ if (memcg && is_classzone) {
shrink_slab(sc->gfp_mask, zone_to_nid(zone),
memcg, sc->nr_scanned - scanned,
lru_pages);
+ if (reclaim_state) {
+ sc->nr_reclaimed +=
+ reclaim_state->reclaimed_slab;
+ reclaim_state->reclaimed_slab = 0;
+ }
+ }
+
/*
* Direct reclaim and kswapd have to scan all memory
* cgroups to fulfill the overall scan target for the
@@ -2467,14 +2474,16 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc,
* Shrink the slab caches in the same proportion that
* the eligible LRU pages were scanned.
*/
- if (global_reclaim(sc) && is_classzone)
+ if (global_reclaim(sc) && is_classzone) {
shrink_slab(sc->gfp_mask, zone_to_nid(zone), NULL,
sc->nr_scanned - nr_scanned,
zone_lru_pages);
- if (reclaim_state) {
- sc->nr_reclaimed += reclaim_state->reclaimed_slab;
- reclaim_state->reclaimed_slab = 0;
+ if (reclaim_state) {
+ sc->nr_reclaimed +=
+ reclaim_state->reclaimed_slab;
+ reclaim_state->reclaimed_slab = 0;
+ }
}
vmpressure(sc->gfp_mask, sc->target_mem_cgroup,
--
2.6.1
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