mm, compaction: prevent infinite loop in compact_zone

[android-x86/kernel.git] / mm / compaction.c

diff --git a/mm/compaction.c b/mm/compaction.c
index ec74cf0..f9792ba 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -479,6 +479,16 @@ isolate_freepages_range(struct compact_control *cc,
 
                block_end_pfn = min(block_end_pfn, end_pfn);
 
+               /*
+                * pfn could pass the block_end_pfn if isolated freepage
+                * is more than pageblock order. In this case, we adjust
+                * scanning range to right one.
+                */
+               if (pfn >= block_end_pfn) {
+                       block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
+                       block_end_pfn = min(block_end_pfn, end_pfn);
+               }
+
                if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))
                        break;
 
@@ -1029,8 +1039,12 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
        }
 
        acct_isolated(zone, cc);
-       /* Record where migration scanner will be restarted */
-       cc->migrate_pfn = low_pfn;
+       /*
+        * Record where migration scanner will be restarted. If we end up in
+        * the same pageblock as the free scanner, make the scanners fully
+        * meet so that compact_finished() terminates compaction.
+        */
+       cc->migrate_pfn = (end_pfn <= cc->free_pfn) ? low_pfn : cc->free_pfn;
 
        return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
 }