1 files changed, 32 insertions, 74 deletions

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index f84f0981b2df..042937d5abe4 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -178,16 +178,10 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_
 	unmovable = has_unmovable_pages(check_unmovable_start, check_unmovable_end,
 			migratetype, isol_flags);
 	if (!unmovable) {
-		int nr_pages;
-		int mt = get_pageblock_migratetype(page);
-
-		nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
-		/* Block spans zone boundaries? */
-		if (nr_pages == -1) {
+		if (!move_freepages_block_isolate(zone, page, MIGRATE_ISOLATE)) {
 			spin_unlock_irqrestore(&zone->lock, flags);
 			return -EBUSY;
 		}
-		__mod_zone_freepage_state(zone, -nr_pages, mt);
 		zone->nr_isolate_pageblock++;
 		spin_unlock_irqrestore(&zone->lock, flags);
 		return 0;
@@ -254,13 +248,11 @@ static void unset_migratetype_isolate(struct page *page, int migratetype)
 	 * allocation.
 	 */
 	if (!isolated_page) {
-		int nr_pages = move_freepages_block(zone, page, migratetype);
 		/*
 		 * Isolating this block already succeeded, so this
 		 * should not fail on zone boundaries.
 		 */
-		WARN_ON_ONCE(nr_pages == -1);
-		__mod_zone_freepage_state(zone, nr_pages, migratetype);
+		WARN_ON_ONCE(!move_freepages_block_isolate(zone, page, migratetype));
 	} else {
 		set_pageblock_migratetype(page, migratetype);
 		__putback_isolated_page(page, order, migratetype);
@@ -374,26 +366,29 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
 
 		VM_BUG_ON(!page);
 		pfn = page_to_pfn(page);
-		/*
-		 * start_pfn is MAX_ORDER_NR_PAGES aligned, if there is any
-		 * free pages in [start_pfn, boundary_pfn), its head page will
-		 * always be in the range.
-		 */
+
 		if (PageBuddy(page)) {
 			int order = buddy_order(page);
 
-			if (pfn + (1UL << order) > boundary_pfn) {
-				/* free page changed before split, check it again */
-				if (split_free_page(page, order, boundary_pfn - pfn))
-					continue;
-			}
+			/* move_freepages_block_isolate() handled this */
+			VM_WARN_ON_ONCE(pfn + (1 << order) > boundary_pfn);
 
 			pfn += 1UL << order;
 			continue;
 		}
+
 		/*
-		 * migrate compound pages then let the free page handling code
-		 * above do the rest. If migration is not possible, just fail.
+		 * If a compound page is straddling our block, attempt
+		 * to migrate it out of the way.
+		 *
+		 * We don't have to worry about this creating a large
+		 * free page that straddles into our block: gigantic
+		 * pages are freed as order-0 chunks, and LRU pages
+		 * (currently) do not exceed pageblock_order.
+		 *
+		 * The block of interest has already been marked
+		 * MIGRATE_ISOLATE above, so when migration is done it
+		 * will free its pages onto the correct freelists.
 		 */
 		if (PageCompound(page)) {
 			struct page *head = compound_head(page);
@@ -404,16 +399,10 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
 				pfn = head_pfn + nr_pages;
 				continue;
 			}
+
 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
-			/*
-			 * hugetlb, lru compound (THP), and movable compound pages
-			 * can be migrated. Otherwise, fail the isolation.
-			 */
-			if (PageHuge(page) || PageLRU(page) || __PageMovable(page)) {
-				int order;
-				unsigned long outer_pfn;
+			if (PageHuge(page)) {
 				int page_mt = get_pageblock_migratetype(page);
-				bool isolate_page = !is_migrate_isolate_page(page);
 				struct compact_control cc = {
 					.nr_migratepages = 0,
 					.order = -1,
@@ -426,56 +415,25 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
 				};
 				INIT_LIST_HEAD(&cc.migratepages);
 
-				/*
-				 * XXX: mark the page as MIGRATE_ISOLATE so that
-				 * no one else can grab the freed page after migration.
-				 * Ideally, the page should be freed as two separate
-				 * pages to be added into separate migratetype free
-				 * lists.
-				 */
-				if (isolate_page) {
-					ret = set_migratetype_isolate(page, page_mt,
-						flags, head_pfn, head_pfn + nr_pages);
-					if (ret)
-						goto failed;
-				}
-
 				ret = __alloc_contig_migrate_range(&cc, head_pfn,
 							head_pfn + nr_pages, page_mt);
-
-				/*
-				 * restore the page's migratetype so that it can
-				 * be split into separate migratetype free lists
-				 * later.
-				 */
-				if (isolate_page)
-					unset_migratetype_isolate(page, page_mt);
-
 				if (ret)
 					goto failed;
-				/*
-				 * reset pfn to the head of the free page, so
-				 * that the free page handling code above can split
-				 * the free page to the right migratetype list.
-				 *
-				 * head_pfn is not used here as a hugetlb page order
-				 * can be bigger than MAX_PAGE_ORDER, but after it is
-				 * freed, the free page order is not. Use pfn within
-				 * the range to find the head of the free page.
-				 */
-				order = 0;
-				outer_pfn = pfn;
-				while (!PageBuddy(pfn_to_page(outer_pfn))) {
-					/* stop if we cannot find the free page */
-					if (++order > MAX_PAGE_ORDER)
-						goto failed;
-					outer_pfn &= ~0UL << order;
-				}
-				pfn = outer_pfn;
+				pfn = head_pfn + nr_pages;
 				continue;
-			} else
+			}
+
+			/*
+			 * These pages are movable too, but they're
+			 * not expected to exceed pageblock_order.
+			 *
+			 * Let us know when they do, so we can add
+			 * proper free and split handling for them.
+			 */
+			VM_WARN_ON_ONCE_PAGE(PageLRU(page), page);
+			VM_WARN_ON_ONCE_PAGE(__PageMovable(page), page);
 #endif
-				goto failed;
+			goto failed;
 		}
 
 		pfn++;