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-rw-r--r--mm/compaction.c35
1 files changed, 20 insertions, 15 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index 32c719a4bc3d..6ce23c966cda 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -948,8 +948,7 @@ static void isolate_freepages(struct compact_control *cc)
* pages on cc->migratepages. We stop searching if the migrate
* and free page scanners meet or enough free pages are isolated.
*/
- for (; block_start_pfn >= low_pfn &&
- cc->nr_migratepages > cc->nr_freepages;
+ for (; block_start_pfn >= low_pfn;
block_end_pfn = block_start_pfn,
block_start_pfn -= pageblock_nr_pages,
isolate_start_pfn = block_start_pfn) {
@@ -986,6 +985,8 @@ static void isolate_freepages(struct compact_control *cc)
break;
/*
+ * If we isolated enough freepages, or aborted due to async
+ * compaction being contended, terminate the loop.
* Remember where the free scanner should restart next time,
* which is where isolate_freepages_block() left off.
* But if it scanned the whole pageblock, isolate_start_pfn
@@ -994,27 +995,31 @@ static void isolate_freepages(struct compact_control *cc)
* In that case we will however want to restart at the start
* of the previous pageblock.
*/
- cc->free_pfn = (isolate_start_pfn < block_end_pfn) ?
- isolate_start_pfn :
- block_start_pfn - pageblock_nr_pages;
-
- /*
- * isolate_freepages_block() might have aborted due to async
- * compaction being contended
- */
- if (cc->contended)
+ if ((cc->nr_freepages >= cc->nr_migratepages)
+ || cc->contended) {
+ if (isolate_start_pfn >= block_end_pfn)
+ isolate_start_pfn =
+ block_start_pfn - pageblock_nr_pages;
break;
+ } else {
+ /*
+ * isolate_freepages_block() should not terminate
+ * prematurely unless contended, or isolated enough
+ */
+ VM_BUG_ON(isolate_start_pfn < block_end_pfn);
+ }
}
/* split_free_page does not map the pages */
map_pages(freelist);
/*
- * If we crossed the migrate scanner, we want to keep it that way
- * so that compact_finished() may detect this
+ * Record where the free scanner will restart next time. Either we
+ * broke from the loop and set isolate_start_pfn based on the last
+ * call to isolate_freepages_block(), or we met the migration scanner
+ * and the loop terminated due to isolate_start_pfn < low_pfn
*/
- if (block_start_pfn < low_pfn)
- cc->free_pfn = cc->migrate_pfn;
+ cc->free_pfn = isolate_start_pfn;
}
/*