mm/compaction: correct to flush migrated pages if pageblock skip happens

[deliverable/linux.git] / mm / compaction.c

diff --git a/mm/compaction.c b/mm/compaction.c
index 8f64d3533990079d65e821cdd11843eaffbf9b17..c5c627aae9962daf9c64d4f482c075e4cd96422a 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1115,6 +1115,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
                                        struct compact_control *cc)
 {
        unsigned long low_pfn, end_pfn;
+       unsigned long isolate_start_pfn;
        struct page *page;
        const isolate_mode_t isolate_mode =
                (sysctl_compact_unevictable_allowed ? ISOLATE_UNEVICTABLE : 0) |
@@ -1163,6 +1164,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
                        continue;
 
                /* Perform the isolation */
+               isolate_start_pfn = low_pfn;
                low_pfn = isolate_migratepages_block(cc, low_pfn, end_pfn,
                                                                isolate_mode);
 
@@ -1171,6 +1173,15 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
                        return ISOLATE_ABORT;
                }
 
+               /*
+                * Record where we could have freed pages by migration and not
+                * yet flushed them to buddy allocator.
+                * - this is the lowest page that could have been isolated and
+                * then freed by migration.
+                */
+               if (cc->nr_migratepages && !cc->last_migrated_pfn)
+                       cc->last_migrated_pfn = isolate_start_pfn;
+
                /*
                 * Either we isolated something and proceed with migration. Or
                 * we failed and compact_zone should decide if we should
@@ -1342,7 +1353,6 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
        unsigned long end_pfn = zone_end_pfn(zone);
        const int migratetype = gfpflags_to_migratetype(cc->gfp_mask);
        const bool sync = cc->mode != MIGRATE_ASYNC;
-       unsigned long last_migrated_pfn = 0;
 
        ret = compaction_suitable(zone, cc->order, cc->alloc_flags,
                                                        cc->classzone_idx);
@@ -1380,6 +1390,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
                zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn;
                zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn;
        }
+       cc->last_migrated_pfn = 0;
 
        trace_mm_compaction_begin(start_pfn, cc->migrate_pfn,
                                cc->free_pfn, end_pfn, sync);
@@ -1389,7 +1400,6 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
        while ((ret = compact_finished(zone, cc, migratetype)) ==
                                                COMPACT_CONTINUE) {
                int err;
-               unsigned long isolate_start_pfn = cc->migrate_pfn;
 
                switch (isolate_migratepages(zone, cc)) {
                case ISOLATE_ABORT:
@@ -1429,16 +1439,6 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
                        }
                }
 
-               /*
-                * Record where we could have freed pages by migration and not
-                * yet flushed them to buddy allocator. We use the pfn that
-                * isolate_migratepages() started from in this loop iteration
-                * - this is the lowest page that could have been isolated and
-                * then freed by migration.
-                */
-               if (!last_migrated_pfn)
-                       last_migrated_pfn = isolate_start_pfn;
-
 check_drain:
                /*
                 * Has the migration scanner moved away from the previous
@@ -1447,18 +1447,18 @@ check_drain:
                 * compact_finished() can detect immediately if allocation
                 * would succeed.
                 */
-               if (cc->order > 0 && last_migrated_pfn) {
+               if (cc->order > 0 && cc->last_migrated_pfn) {
                        int cpu;
                        unsigned long current_block_start =
                                cc->migrate_pfn & ~((1UL << cc->order) - 1);
 
-                       if (last_migrated_pfn < current_block_start) {
+                       if (cc->last_migrated_pfn < current_block_start) {
                                cpu = get_cpu();
                                lru_add_drain_cpu(cpu);
                                drain_local_pages(zone);
                                put_cpu();
                                /* No more flushing until we migrate again */
-                               last_migrated_pfn = 0;
+                               cc->last_migrated_pfn = 0;
                        }
                }