1 files changed, 74 insertions, 33 deletions

diff --git a/mm/compaction.c b/mm/compaction.c
index e04f4476e68e..3a6c6b821f80 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -787,15 +787,14 @@ static bool too_many_isolated(pg_data_t *pgdat)
  *
  * Isolate all pages that can be migrated from the range specified by
  * [low_pfn, end_pfn). The range is expected to be within same pageblock.
- * Returns zero if there is a fatal signal pending, otherwise PFN of the
- * first page that was not scanned (which may be both less, equal to or more
- * than end_pfn).
+ * Returns errno, like -EAGAIN or -EINTR in case e.g signal pending or congestion,
+ * -ENOMEM in case we could not allocate a page, or 0.
+ * cc->migrate_pfn will contain the next pfn to scan.
  *
  * The pages are isolated on cc->migratepages list (not required to be empty),
- * and cc->nr_migratepages is updated accordingly. The cc->migrate_pfn field
- * is neither read nor updated.
+ * and cc->nr_migratepages is updated accordingly.
  */
-static unsigned long
+static int
 isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 			unsigned long end_pfn, isolate_mode_t isolate_mode)
 {
@@ -809,6 +808,9 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 	bool skip_on_failure = false;
 	unsigned long next_skip_pfn = 0;
 	bool skip_updated = false;
+	int ret = 0;
+
+	cc->migrate_pfn = low_pfn;
 
 	/*
 	 * Ensure that there are not too many pages isolated from the LRU
@@ -818,16 +820,16 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 	while (unlikely(too_many_isolated(pgdat))) {
 		/* stop isolation if there are still pages not migrated */
 		if (cc->nr_migratepages)
-			return 0;
+			return -EAGAIN;
 
 		/* async migration should just abort */
 		if (cc->mode == MIGRATE_ASYNC)
-			return 0;
+			return -EAGAIN;
 
 		congestion_wait(BLK_RW_ASYNC, HZ/10);
 
 		if (fatal_signal_pending(current))
-			return 0;
+			return -EINTR;
 	}
 
 	cond_resched();
@@ -875,8 +877,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 
 			if (fatal_signal_pending(current)) {
 				cc->contended = true;
+				ret = -EINTR;
 
-				low_pfn = 0;
 				goto fatal_pending;
 			}
 
@@ -904,6 +906,38 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 			valid_page = page;
 		}
 
+		if (PageHuge(page) && cc->alloc_contig) {
+			ret = isolate_or_dissolve_huge_page(page, &cc->migratepages);
+
+			/*
+			 * Fail isolation in case isolate_or_dissolve_huge_page()
+			 * reports an error. In case of -ENOMEM, abort right away.
+			 */
+			if (ret < 0) {
+				 /* Do not report -EBUSY down the chain */
+				if (ret == -EBUSY)
+					ret = 0;
+				low_pfn += (1UL << compound_order(page)) - 1;
+				goto isolate_fail;
+			}
+
+			if (PageHuge(page)) {
+				/*
+				 * Hugepage was successfully isolated and placed
+				 * on the cc->migratepages list.
+				 */
+				low_pfn += compound_nr(page) - 1;
+				goto isolate_success_no_list;
+			}
+
+			/*
+			 * Ok, the hugepage was dissolved. Now these pages are
+			 * Buddy and cannot be re-allocated because they are
+			 * isolated. Fall-through as the check below handles
+			 * Buddy pages.
+			 */
+		}
+
 		/*
 		 * Skip if free. We read page order here without zone lock
 		 * which is generally unsafe, but the race window is small and
@@ -1037,6 +1071,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 
 isolate_success:
 		list_add(&page->lru, &cc->migratepages);
+isolate_success_no_list:
 		cc->nr_migratepages += compound_nr(page);
 		nr_isolated += compound_nr(page);
 
@@ -1063,7 +1098,7 @@ isolate_fail_put:
 		put_page(page);
 
 isolate_fail:
-		if (!skip_on_failure)
+		if (!skip_on_failure && ret != -ENOMEM)
 			continue;
 
 		/*
@@ -1089,6 +1124,9 @@ isolate_fail:
 			 */
 			next_skip_pfn += 1UL << cc->order;
 		}
+
+		if (ret == -ENOMEM)
+			break;
 	}
 
 	/*
@@ -1130,7 +1168,9 @@ fatal_pending:
 	if (nr_isolated)
 		count_compact_events(COMPACTISOLATED, nr_isolated);
 
-	return low_pfn;
+	cc->migrate_pfn = low_pfn;
+
+	return ret;
 }
 
 /**
@@ -1139,15 +1179,15 @@ fatal_pending:
  * @start_pfn: The first PFN to start isolating.
  * @end_pfn:   The one-past-last PFN.
  *
- * Returns zero if isolation fails fatally due to e.g. pending signal.
- * Otherwise, function returns one-past-the-last PFN of isolated page
- * (which may be greater than end_pfn if end fell in a middle of a THP page).
+ * Returns -EAGAIN when contented, -EINTR in case of a signal pending, -ENOMEM
+ * in case we could not allocate a page, or 0.
  */
-unsigned long
+int
 isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,
 							unsigned long end_pfn)
 {
 	unsigned long pfn, block_start_pfn, block_end_pfn;
+	int ret = 0;
 
 	/* Scan block by block. First and last block may be incomplete */
 	pfn = start_pfn;
@@ -1166,17 +1206,17 @@ isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,
 					block_end_pfn, cc->zone))
 			continue;
 
-		pfn = isolate_migratepages_block(cc, pfn, block_end_pfn,
-							ISOLATE_UNEVICTABLE);
+		ret = isolate_migratepages_block(cc, pfn, block_end_pfn,
+						 ISOLATE_UNEVICTABLE);
 
-		if (!pfn)
+		if (ret)
 			break;
 
 		if (cc->nr_migratepages >= COMPACT_CLUSTER_MAX)
 			break;
 	}
 
-	return pfn;
+	return ret;
 }
 
 #endif /* CONFIG_COMPACTION || CONFIG_CMA */
@@ -1847,7 +1887,7 @@ static isolate_migrate_t isolate_migratepages(struct compact_control *cc)
 	 */
 	for (; block_end_pfn <= cc->free_pfn;
 			fast_find_block = false,
-			low_pfn = block_end_pfn,
+			cc->migrate_pfn = low_pfn = block_end_pfn,
 			block_start_pfn = block_end_pfn,
 			block_end_pfn += pageblock_nr_pages) {
 
@@ -1889,10 +1929,8 @@ static isolate_migrate_t isolate_migratepages(struct compact_control *cc)
 		}
 
 		/* Perform the isolation */
-		low_pfn = isolate_migratepages_block(cc, low_pfn,
-						block_end_pfn, isolate_mode);
-
-		if (!low_pfn)
+		if (isolate_migratepages_block(cc, low_pfn, block_end_pfn,
+						isolate_mode))
 			return ISOLATE_ABORT;
 
 		/*
@@ -1903,9 +1941,6 @@ static isolate_migrate_t isolate_migratepages(struct compact_control *cc)
 		break;
 	}
 
-	/* Record where migration scanner will be restarted. */
-	cc->migrate_pfn = low_pfn;
-
 	return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
 }
 
@@ -2319,7 +2354,8 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
 	trace_mm_compaction_begin(start_pfn, cc->migrate_pfn,
 				cc->free_pfn, end_pfn, sync);
 
-	migrate_prep_local();
+	/* lru_add_drain_all could be expensive with involving other CPUs */
+	lru_add_drain();
 
 	while ((ret = compact_finished(cc)) == COMPACT_CONTINUE) {
 		int err;
@@ -2494,6 +2530,14 @@ static enum compact_result compact_zone_order(struct zone *zone, int order,
 	 */
 	WRITE_ONCE(current->capture_control, NULL);
 	*capture = READ_ONCE(capc.page);
+	/*
+	 * Technically, it is also possible that compaction is skipped but
+	 * the page is still captured out of luck(IRQ came and freed the page).
+	 * Returning COMPACT_SUCCESS in such cases helps in properly accounting
+	 * the COMPACT[STALL|FAIL] when compaction is skipped.
+	 */
+	if (*capture)
+		ret = COMPACT_SUCCESS;
 
 	return ret;
 }
@@ -2657,9 +2701,6 @@ static void compact_nodes(void)
 		compact_node(nid);
 }
 
-/* The written value is actually unused, all memory is compacted */
-int sysctl_compact_memory;
-
 /*
  * Tunable for proactive compaction. It determines how
  * aggressively the kernel should compact memory in the
@@ -2844,7 +2885,7 @@ void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx)
  */
 static int kcompactd(void *p)
 {
-	pg_data_t *pgdat = (pg_data_t*)p;
+	pg_data_t *pgdat = (pg_data_t *)p;
 	struct task_struct *tsk = current;
 	unsigned int proactive_defer = 0;