The should_continue_reclaim() function decides during direct reclaim/compaction
whether shrink_zone() should continue reclaming, or whether compaction is ready
to proceed in that zone. This relies mainly on the compaction_suitable() check,
but by passing a zero classzone_idx, there can be false positives and reclaim
terminates prematurely. Fix this by passing proper classzone_idx.
Additionally, the function checks whether (2UL << pages) were reclaimed. This
however overlaps with the same gap used by compaction_suitable(), and since the
number sc->nr_reclaimed is accumulated over all reclaimed zones, it doesn't
make much sense for deciding about a given single zone anyway. So just drop
this code.
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/vmscan.c | 31 +++++++++----------------------
1 file changed, 9 insertions(+), 22 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 640d2e615c36..391e5d2c4e32 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2309,11 +2309,9 @@ static bool in_reclaim_compaction(struct scan_control *sc)
static inline bool should_continue_reclaim(struct zone *zone,
unsigned long nr_reclaimed,
unsigned long nr_scanned,
- struct scan_control *sc)
+ struct scan_control *sc,
+ int classzone_idx)
{
- unsigned long pages_for_compaction;
- unsigned long inactive_lru_pages;
-
/* If not in reclaim/compaction mode, stop */
if (!in_reclaim_compaction(sc))
return false;
@@ -2341,20 +2339,8 @@ static inline bool should_continue_reclaim(struct zone *zone,
return false;
}
- /*
- * If we have not reclaimed enough pages for compaction and the
- * inactive lists are large enough, continue reclaiming
- */
- pages_for_compaction = compact_gap(sc->order);
- inactive_lru_pages = zone_page_state(zone, NR_INACTIVE_FILE);
- if (get_nr_swap_pages() > 0)
- inactive_lru_pages += zone_page_state(zone, NR_INACTIVE_ANON);
- if (sc->nr_reclaimed < pages_for_compaction &&
- inactive_lru_pages > pages_for_compaction)
- return true;
-
/* If compaction would go ahead or the allocation would succeed, stop */
- switch (compaction_suitable(zone, sc->order, 0, 0)) {
+ switch (compaction_suitable(zone, sc->order, 0, classzone_idx)) {
case COMPACT_PARTIAL:
case COMPACT_CONTINUE:
return false;
@@ -2364,11 +2350,12 @@ static inline bool should_continue_reclaim(struct zone *zone,
}
static bool shrink_zone(struct zone *zone, struct scan_control *sc,
- bool is_classzone)
+ int classzone_idx)
{
struct reclaim_state *reclaim_state = current->reclaim_state;
unsigned long nr_reclaimed, nr_scanned;
bool reclaimable = false;
+ bool is_classzone = (classzone_idx == zone_idx(zone));
do {
struct mem_cgroup *root = sc->target_mem_cgroup;
@@ -2450,7 +2437,7 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc,
reclaimable = true;
} while (should_continue_reclaim(zone, sc->nr_reclaimed - nr_reclaimed,
- sc->nr_scanned - nr_scanned, sc));
+ sc->nr_scanned - nr_scanned, sc, classzone_idx));
return reclaimable;
}
@@ -2580,7 +2567,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
/* need some check for avoid more shrink_zone() */
}
- shrink_zone(zone, sc, zone_idx(zone) == classzone_idx);
+ shrink_zone(zone, sc, classzone_idx);
}
/*
@@ -3076,7 +3063,7 @@ static bool kswapd_shrink_zone(struct zone *zone,
balance_gap, classzone_idx))
return true;
- shrink_zone(zone, sc, zone_idx(zone) == classzone_idx);
+ shrink_zone(zone, sc, classzone_idx);
clear_bit(ZONE_WRITEBACK, &zone->flags);
@@ -3678,7 +3665,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
* priorities until we have enough memory freed.
*/
do {
- shrink_zone(zone, &sc, true);
+ shrink_zone(zone, &sc, zone_idx(zone));
} while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0);
}
--
2.8.3
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