[PATCH v2 2/4] mm/page_isolation: remove migratetype from move_freepages_block_isolate()

[Zi Yan <ziy@nvidia.com>]

Since migratetype is no longer overwritten during pageblock isolation,
moving pageblocks to and from MIGRATE_ISOLATE do not need migratetype.

Rename move_freepages_block_isolate() to share common code and add
pageblock_isolate_and_move_free_pages() and
pageblock_unisolate_and_move_free_pages() to be explicit about the page
isolation operations.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
 include/linux/page-isolation.h |  4 +--
 mm/page_alloc.c                | 48 +++++++++++++++++++++++++++-------
 mm/page_isolation.c            | 21 +++++++--------
 3 files changed, 51 insertions(+), 22 deletions(-)

diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
index 51797dc39cbc..28c56f423e34 100644
--- a/include/linux/page-isolation.h
+++ b/include/linux/page-isolation.h
@@ -27,8 +27,8 @@ static inline bool is_migrate_isolate(int migratetype)
 
 void set_pageblock_migratetype(struct page *page, int migratetype);
 
-bool move_freepages_block_isolate(struct zone *zone, struct page *page,
-				  int migratetype);
+bool pageblock_isolate_and_move_free_pages(struct zone *zone, struct page *page);
+bool pageblock_unisolate_and_move_free_pages(struct zone *zone, struct page *page);
 
 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 			     int migratetype, int flags);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f17f4acc38c6..9bba5b1c4f1d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1848,10 +1848,10 @@ static unsigned long find_large_buddy(unsigned long start_pfn)
 }
 
 /**
- * move_freepages_block_isolate - move free pages in block for page isolation
+ * __move_freepages_for_page_isolation - move free pages in block for page isolation
  * @zone: the zone
  * @page: the pageblock page
- * @migratetype: migratetype to set on the pageblock
+ * @isolate_pageblock to isolate the given pageblock or unisolate it
  *
  * This is similar to move_freepages_block(), but handles the special
  * case encountered in page isolation, where the block of interest
@@ -1866,10 +1866,15 @@ static unsigned long find_large_buddy(unsigned long start_pfn)
  *
  * Returns %true if pages could be moved, %false otherwise.
  */
-bool move_freepages_block_isolate(struct zone *zone, struct page *page,
-				  int migratetype)
+static bool __move_freepages_for_page_isolation(struct zone *zone,
+		struct page *page, bool isolate_pageblock)
 {
 	unsigned long start_pfn, pfn;
+	int from_mt;
+	int to_mt;
+
+	if (isolate_pageblock == get_pageblock_isolate(page))
+		return false;
 
 	if (!prep_move_freepages_block(zone, page, &start_pfn, NULL, NULL))
 		return false;
@@ -1886,7 +1891,10 @@ bool move_freepages_block_isolate(struct zone *zone, struct page *page,
 
 		del_page_from_free_list(buddy, zone, order,
 					get_pfnblock_migratetype(buddy, pfn));
-		set_pageblock_migratetype(page, migratetype);
+		if (isolate_pageblock)
+			set_pageblock_isolate(page);
+		else
+			clear_pageblock_isolate(page);
 		split_large_buddy(zone, buddy, pfn, order, FPI_NONE);
 		return true;
 	}
@@ -1897,16 +1905,38 @@ bool move_freepages_block_isolate(struct zone *zone, struct page *page,
 
 		del_page_from_free_list(page, zone, order,
 					get_pfnblock_migratetype(page, pfn));
-		set_pageblock_migratetype(page, migratetype);
+		if (isolate_pageblock)
+			set_pageblock_isolate(page);
+		else
+			clear_pageblock_isolate(page);
 		split_large_buddy(zone, page, pfn, order, FPI_NONE);
 		return true;
 	}
 move:
-	__move_freepages_block(zone, start_pfn,
-			       get_pfnblock_migratetype(page, start_pfn),
-			       migratetype);
+	if (isolate_pageblock) {
+		from_mt = __get_pfnblock_flags_mask(page, page_to_pfn(page),
+				MIGRATETYPE_MASK);
+		to_mt = MIGRATE_ISOLATE;
+	} else {
+		from_mt = MIGRATE_ISOLATE;
+		to_mt = __get_pfnblock_flags_mask(page, page_to_pfn(page),
+				MIGRATETYPE_MASK);
+	}
+
+	__move_freepages_block(zone, start_pfn, from_mt, to_mt);
 	return true;
 }
+
+bool pageblock_isolate_and_move_free_pages(struct zone *zone, struct page *page)
+{
+	return __move_freepages_for_page_isolation(zone, page, true);
+}
+
+bool pageblock_unisolate_and_move_free_pages(struct zone *zone, struct page *page)
+{
+	return __move_freepages_for_page_isolation(zone, page, false);
+}
+
 #endif /* CONFIG_MEMORY_ISOLATION */
 
 static void change_pageblock_range(struct page *pageblock_page,
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 8ed53ee00f2a..01d9a4eace7a 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -188,7 +188,7 @@ 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) {
-		if (!move_freepages_block_isolate(zone, page, MIGRATE_ISOLATE)) {
+		if (!pageblock_isolate_and_move_free_pages(zone, page)) {
 			spin_unlock_irqrestore(&zone->lock, flags);
 			return -EBUSY;
 		}
@@ -209,7 +209,7 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_
 	return -EBUSY;
 }
 
-static void unset_migratetype_isolate(struct page *page, int migratetype)
+static void unset_migratetype_isolate(struct page *page)
 {
 	struct zone *zone;
 	unsigned long flags;
@@ -262,10 +262,10 @@ static void unset_migratetype_isolate(struct page *page, int migratetype)
 		 * Isolating this block already succeeded, so this
 		 * should not fail on zone boundaries.
 		 */
-		WARN_ON_ONCE(!move_freepages_block_isolate(zone, page, migratetype));
+		WARN_ON_ONCE(!pageblock_unisolate_and_move_free_pages(zone, page));
 	} else {
-		set_pageblock_migratetype(page, migratetype);
-		__putback_isolated_page(page, order, migratetype);
+		clear_pageblock_isolate(page);
+		__putback_isolated_page(page, order, get_pageblock_migratetype(page));
 	}
 	zone->nr_isolate_pageblock--;
 out:
@@ -383,7 +383,7 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
 		if (PageBuddy(page)) {
 			int order = buddy_order(page);
 
-			/* move_freepages_block_isolate() handled this */
+			/* pageblock_isolate_and_move_free_pages() handled this */
 			VM_WARN_ON_ONCE(pfn + (1 << order) > boundary_pfn);
 
 			pfn += 1UL << order;
@@ -433,7 +433,7 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
 failed:
 	/* restore the original migratetype */
 	if (!skip_isolation)
-		unset_migratetype_isolate(pfn_to_page(isolate_pageblock), migratetype);
+		unset_migratetype_isolate(pfn_to_page(isolate_pageblock));
 	return -EBUSY;
 }
 
@@ -504,7 +504,7 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 	ret = isolate_single_pageblock(isolate_end, flags, true,
 			skip_isolation, migratetype);
 	if (ret) {
-		unset_migratetype_isolate(pfn_to_page(isolate_start), migratetype);
+		unset_migratetype_isolate(pfn_to_page(isolate_start));
 		return ret;
 	}
 
@@ -517,8 +517,7 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 					start_pfn, end_pfn)) {
 			undo_isolate_page_range(isolate_start, pfn, migratetype);
 			unset_migratetype_isolate(
-				pfn_to_page(isolate_end - pageblock_nr_pages),
-				migratetype);
+				pfn_to_page(isolate_end - pageblock_nr_pages));
 			return -EBUSY;
 		}
 	}
@@ -548,7 +547,7 @@ void undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 		page = __first_valid_page(pfn, pageblock_nr_pages);
 		if (!page || !is_migrate_isolate_page(page))
 			continue;
-		unset_migratetype_isolate(page, migratetype);
+		unset_migratetype_isolate(page);
 	}
 }
 /*
-- 
2.47.2