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mm, vmscan: only allocate and reclaim from zones with pages managed by the buddy allocator

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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 1d82de618d ("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.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Mel Gorman <[email protected]>
Reported-by: Srikar Dronamraju <[email protected]>
Tested-by: Srikar Dronamraju <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Mel Gorman 2016-09-01 16:14:55 -07:00 • committed by Linus Torvalds
commit 6aa303defb
3 changed files with 27 additions and 15 deletions
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22
mm/vmscan.c
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@ -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))