1 files changed, 80 insertions, 9 deletions

diff --git a/mm/compaction.c b/mm/compaction.c
index 329973a1ae45..7487067b4613 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -638,12 +638,13 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 {
 	struct zone *zone = cc->zone;
 	unsigned long nr_scanned = 0, nr_isolated = 0;
-	struct list_head *migratelist = &cc->migratepages;
 	struct lruvec *lruvec;
 	unsigned long flags = 0;
 	bool locked = false;
 	struct page *page = NULL, *valid_page = NULL;
 	unsigned long start_pfn = low_pfn;
+	bool skip_on_failure = false;
+	unsigned long next_skip_pfn = 0;
 
 	/*
 	 * Ensure that there are not too many pages isolated from the LRU
@@ -664,10 +665,37 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 	if (compact_should_abort(cc))
 		return 0;
 
+	if (cc->direct_compaction && (cc->mode == MIGRATE_ASYNC)) {
+		skip_on_failure = true;
+		next_skip_pfn = block_end_pfn(low_pfn, cc->order);
+	}
+
 	/* Time to isolate some pages for migration */
 	for (; low_pfn < end_pfn; low_pfn++) {
 		bool is_lru;
 
+		if (skip_on_failure && low_pfn >= next_skip_pfn) {
+			/*
+			 * We have isolated all migration candidates in the
+			 * previous order-aligned block, and did not skip it due
+			 * to failure. We should migrate the pages now and
+			 * hopefully succeed compaction.
+			 */
+			if (nr_isolated)
+				break;
+
+			/*
+			 * We failed to isolate in the previous order-aligned
+			 * block. Set the new boundary to the end of the
+			 * current block. Note we can't simply increase
+			 * next_skip_pfn by 1 << order, as low_pfn might have
+			 * been incremented by a higher number due to skipping
+			 * a compound or a high-order buddy page in the
+			 * previous loop iteration.
+			 */
+			next_skip_pfn = block_end_pfn(low_pfn, cc->order);
+		}
+
 		/*
 		 * Periodically drop the lock (if held) regardless of its
 		 * contention, to give chance to IRQs. Abort async compaction
@@ -679,7 +707,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 			break;
 
 		if (!pfn_valid_within(low_pfn))
-			continue;
+			goto isolate_fail;
 		nr_scanned++;
 
 		page = pfn_to_page(low_pfn);
@@ -734,11 +762,11 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 			if (likely(comp_order < MAX_ORDER))
 				low_pfn += (1UL << comp_order) - 1;
 
-			continue;
+			goto isolate_fail;
 		}
 
 		if (!is_lru)
-			continue;
+			goto isolate_fail;
 
 		/*
 		 * Migration will fail if an anonymous page is pinned in memory,
@@ -747,7 +775,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 		 */
 		if (!page_mapping(page) &&
 		    page_count(page) > page_mapcount(page))
-			continue;
+			goto isolate_fail;
 
 		/* If we already hold the lock, we can skip some rechecking */
 		if (!locked) {
@@ -758,7 +786,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 
 			/* Recheck PageLRU and PageCompound under lock */
 			if (!PageLRU(page))
-				continue;
+				goto isolate_fail;
 
 			/*
 			 * Page become compound since the non-locked check,
@@ -767,7 +795,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 			 */
 			if (unlikely(PageCompound(page))) {
 				low_pfn += (1UL << compound_order(page)) - 1;
-				continue;
+				goto isolate_fail;
 			}
 		}
 
@@ -775,7 +803,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 
 		/* Try isolate the page */
 		if (__isolate_lru_page(page, isolate_mode) != 0)
-			continue;
+			goto isolate_fail;
 
 		VM_BUG_ON_PAGE(PageCompound(page), page);
 
@@ -783,7 +811,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 		del_page_from_lru_list(page, lruvec, page_lru(page));
 
 isolate_success:
-		list_add(&page->lru, migratelist);
+		list_add(&page->lru, &cc->migratepages);
 		cc->nr_migratepages++;
 		nr_isolated++;
 
@@ -801,6 +829,37 @@ isolate_success:
 			++low_pfn;
 			break;
 		}
+
+		continue;
+isolate_fail:
+		if (!skip_on_failure)
+			continue;
+
+		/*
+		 * We have isolated some pages, but then failed. Release them
+		 * instead of migrating, as we cannot form the cc->order buddy
+		 * page anyway.
+		 */
+		if (nr_isolated) {
+			if (locked) {
+				spin_unlock_irqrestore(&zone->lru_lock,	flags);
+				locked = false;
+			}
+			acct_isolated(zone, cc);
+			putback_movable_pages(&cc->migratepages);
+			cc->nr_migratepages = 0;
+			cc->last_migrated_pfn = 0;
+			nr_isolated = 0;
+		}
+
+		if (low_pfn < next_skip_pfn) {
+			low_pfn = next_skip_pfn - 1;
+			/*
+			 * The check near the loop beginning would have updated
+			 * next_skip_pfn too, but this is a bit simpler.
+			 */
+			next_skip_pfn += 1UL << cc->order;
+		}
 	}
 
 	/*
@@ -1401,6 +1460,18 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 				ret = COMPACT_CONTENDED;
 				goto out;
 			}
+			/*
+			 * We failed to migrate at least one page in the current
+			 * order-aligned block, so skip the rest of it.
+			 */
+			if (cc->direct_compaction &&
+						(cc->mode == MIGRATE_ASYNC)) {
+				cc->migrate_pfn = block_end_pfn(
+						cc->migrate_pfn - 1, cc->order);
+				/* Draining pcplists is useless in this case */
+				cc->last_migrated_pfn = 0;
+
+			}
 		}
 
 check_drain: