2 files changed, 16 insertions, 15 deletions

diff --git a/mm/compaction.c b/mm/compaction.c
index 8f64d3533990..c5c627aae996 100644
--- 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);
 
@@ -1172,6 +1174,15 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
                 }
 
                 /*
+                 * 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
                  * continue or not.
@@ -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;
                         }
                 }
 
diff --git a/mm/internal.h b/mm/internal.h
index 1195dd2d6a2b..bc0fa9a69e46 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -182,6 +182,7 @@ struct compact_control {
         unsigned long nr_migratepages;  /* Number of pages to migrate */
         unsigned long free_pfn;         /* isolate_freepages search base */
         unsigned long migrate_pfn;      /* isolate_migratepages search base */
+        unsigned long last_migrated_pfn;/* Not yet flushed page being freed */
         enum migrate_mode mode;         /* Async or sync migration mode */
         bool ignore_skip_hint;          /* Scan blocks even if marked skip */
         int order;                      /* order a direct compactor needs */