mm, vmscan: Only allocate and reclaim from zones with pages managed by the buddy allocator
Subsystems (5)
PATCH 1/1 mm, vmscan: Only allocate and reclaim from zones with pages managed by the buddy allocator
Firmware Assisted Dump (FA_DUMP) on ppc64 reserves substantial amounts of memory when booting a secondary kernel. Srikar Dronamraju reported that multiple nodes may have no memory managed by the buddy allocator but still return true for populated_zone().
Commit 1d82de618ddd ("mm, vmscan: make kswapd reclaim in terms of nodes") was reported to cause kswapd to spin at 100% CPU usage when fadump was enabled. The old code happened to deal with the situation of a populated node with zero free pages by co-incidence but the current code tries to reclaim populated zones without realising that is impossible.
We cannot just convert populated_zone() as many existing users really need to check for present_pages. This patch introduces a managed_zone() helper and uses it in the few cases where it is critical that the check is made for managed pages -- zonelist construction and page reclaim.
Signed-off-by Mel Gorman <[email protected]>
Reported-and-tested-by Srikar Dronamraju <[email protected]>
Acked-by Michal Hocko <[email protected]>
--- include/linux/mmzone.h | 16 ++++++++++++++-- mm/page_alloc.c | 4 ++-- mm/vmscan.c | 22 +++++++++++----------- 3 files changed, 27 insertions(+), 15 deletions(-)
include/linux/mmzone.h +14 -2
@@ -828,9 +828,21 @@ unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);*/ #define zone_idx (zone) ((zone) - (zone)->zone_pgdat->node_zones) -static inline int populated_zone (struct zone *zone) +/* +* Returns true if a zone has pages managed by the buddy allocator. +* All the reclaim decisions have to use this function rather than +* populated_zone(). If the whole zone is reserved then we can easily +* end up with populated_zone() && !managed_zone(). +*/ +static inline bool managed_zone (struct zone *zone) +{ +return zone->managed_pages; +} + +/* Returns true if a zone has memory */ +static inline bool populated_zone (struct zone *zone) { -return (!!zone->present_pages); +return zone->present_pages; }extern int movable_zone;
mm/page_alloc.c +2 -2
@@ -4407,7 +4407,7 @@ static int build_zonelists_node(pg_data_t *pgdat, struct zonelist *zonelist, do { zone_type--; zone = pgdat->node_zones + zone_type; - if (populated_zone(zone)) { + if (managed_zone(zone)) { zoneref_set_zone(zone, &zonelist->_zonerefs[nr_zones++]); check_highest_zone(zone_type);
@@ -4645,7 +4645,7 @@ static void build_zonelists_in_zone_order(pg_data_t *pgdat, int nr_nodes)for (j =0 ; j < nr_nodes; j++) { node = node_order[j]; z = &NODE_DATA (node)->node_zones[zone_type]; -if (populated_zone (z)) { +if (managed_zone (z)) {zoneref_set_zone (z, &zonelist->_zonerefs[pos++]);check_highest_zone (zone_type);
mm/vmscan.c +11 -11
@@ -1665,7 +1665,7 @@ static bool inactive_reclaimable_pages(struct lruvec *lruvec,for (zid = sc->reclaim_idx; zid >=0 ; zid--) { zone = &pgdat->node_zones[zid]; -if (!populated_zone (zone)) +if (!managed_zone (zone))continue ; if (zone_page_state_snapshot(zone, NR_ZONE_LRU_BASE +
@@ -2036,7 +2036,7 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,struct zone *zone = &pgdat->node_zones[zid];unsigned long inactive_zone, active_zone; -if (!populated_zone (zone)) +if (!managed_zone (zone))continue ; inactive_zone = zone_page_state(zone,
@@ -2171,7 +2171,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,for (z =0 ; z <MAX_NR_ZONES ; z++) {struct zone *zone = &pgdat->node_zones[z]; -if (!populated_zone (zone)) +if (!managed_zone (zone))continue ; total_high_wmark +=high_wmark_pages (zone);
@@ -2510,7 +2510,7 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat,/* If compaction would go ahead or the allocation would succeed, stop */ for (z =0 ; z <= sc->reclaim_idx; z++) {struct zone *zone = &pgdat->node_zones[z]; -if (!populated_zone (zone)) +if (!managed_zone (zone))continue ;switch (compaction_suitable (zone, sc->order,0 , sc->reclaim_idx)) {
@@ -2840,7 +2840,7 @@ static bool pfmemalloc_watermark_ok(pg_data_t *pgdat)for (i =0 ; i <=ZONE_NORMAL ; i++) { zone = &pgdat->node_zones[i]; -if (!populated_zone (zone) || +if (!managed_zone (zone) ||pgdat_reclaimable_pages (pgdat) ==0 )continue ;
@@ -3141,7 +3141,7 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, int classzone_idx)for (i =0 ; i <= classzone_idx; i++) {struct zone *zone = pgdat->node_zones + i; -if (!populated_zone (zone)) +if (!managed_zone (zone))continue ;if (!zone_balanced (zone, order, classzone_idx))
@@ -3169,7 +3169,7 @@ static bool kswapd_shrink_node(pg_data_t *pgdat, sc->nr_to_reclaim =0 ;for (z =0 ; z <= sc->reclaim_idx; z++) { zone = pgdat->node_zones + z; -if (!populated_zone (zone)) +if (!managed_zone (zone))continue ; sc->nr_to_reclaim +=max (high_wmark_pages (zone),SWAP_CLUSTER_MAX );
@@ -3242,7 +3242,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)if (buffer_heads_over_limit) {for (i =MAX_NR_ZONES -1 ; i >=0 ; i--) { zone = pgdat->node_zones + i; -if (!populated_zone (zone)) +if (!managed_zone (zone))continue ; sc.reclaim_idx = i;
@@ -3262,7 +3262,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)*/ for (i = classzone_idx; i >=0 ; i--) { zone = pgdat->node_zones + i; -if (!populated_zone (zone)) +if (!managed_zone (zone))continue ;if (zone_balanced (zone, sc.order, classzone_idx))
@@ -3508,7 +3508,7 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)pg_data_t *pgdat;int z; -if (!populated_zone (zone)) +if (!managed_zone (zone))return ;if (!cpuset_zone_allowed (zone,GFP_KERNEL | __GFP_HARDWALL))
@@ -3522,7 +3522,7 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)/* Only wake kswapd if all zones are unbalanced */ for (z =0 ; z <= classzone_idx; z++) { zone = pgdat->node_zones + z; -if (!populated_zone (zone)) +if (!managed_zone (zone))continue ;if (zone_balanced (zone, order, classzone_idx))
--
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