mm/page_isolation: remove migratetype from move_freepages_block_isolate()

Since migratetype is no longer overwritten during pageblock isolation,
moving a pageblock out of MIGRATE_ISOLATE no longer needs a new
migratetype.

Add pageblock_isolate_and_move_free_pages() and
pageblock_unisolate_and_move_free_pages() to be explicit about the page
isolation operations.  Both share the common code in
__move_freepages_block_isolate(), which is renamed from
move_freepages_block_isolate().

Add toggle_pageblock_isolate() to flip pageblock isolation bit in
__move_freepages_block_isolate().

Make set_pageblock_migratetype() only accept non MIGRATE_ISOLATE types, so
that one should use set_pageblock_isolate() to isolate pageblocks.  As a
result, move pageblock migratetype code out of __move_freepages_block().

Link: https://lkml.kernel.org/r/20250617021115.2331563-5-ziy@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Richard Chang <richardycc@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: x-y-z

include/linux/page-isolation.h

@@ -44,10 +44,9 @@ static inline void set_pageblock_isolate(struct page *page)
 void __meminit init_pageblock_migratetype(struct page *page,
 					  enum migratetype migratetype,
 					  bool isolate);
-void set_pageblock_migratetype(struct page *page, enum migratetype 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);

mm/page_alloc.c

@@ -525,18 +525,22 @@ void clear_pfnblock_bit(const struct page *page, unsigned long pfn,
  * @page: The page within the block of interest
  * @migratetype: migratetype to set
  */
-__always_inline void set_pageblock_migratetype(struct page *page,
-					       enum migratetype migratetype)
+static void set_pageblock_migratetype(struct page *page,
+				      enum migratetype migratetype)
 {
 	if (unlikely(page_group_by_mobility_disabled &&
 		     migratetype < MIGRATE_PCPTYPES))
 		migratetype = MIGRATE_UNMOVABLE;
 
 #ifdef CONFIG_MEMORY_ISOLATION
 	if (migratetype == MIGRATE_ISOLATE) {
-		set_pfnblock_bit(page, page_to_pfn(page), PB_migrate_isolate);
+		VM_WARN_ONCE(1,
+			"Use set_pageblock_isolate() for pageblock isolation");
 		return;
 	}
+	VM_WARN_ONCE(get_pfnblock_bit(page, page_to_pfn(page),
+				      PB_migrate_isolate),
+		     "Use clear_pageblock_isolate() to unisolate pageblock");
 	/* MIGRATETYPE_AND_ISO_MASK clears PB_migrate_isolate if it is set */
 #endif
 	__set_pfnblock_flags_mask(page, page_to_pfn(page),
@@ -1921,8 +1925,8 @@ static inline struct page *__rmqueue_cma_fallback(struct zone *zone,
 #endif
 
 /*
- * Change the type of a block and move all its free pages to that
- * type's freelist.
+ * Move all free pages of a block to new type's freelist. Caller needs to
+ * change the block type.
  */
 static int __move_freepages_block(struct zone *zone, unsigned long start_pfn,
 				  int old_mt, int new_mt)
@@ -1954,8 +1958,6 @@ static int __move_freepages_block(struct zone *zone, unsigned long start_pfn,
 		pages_moved += 1 << order;
 	}
 
-	set_pageblock_migratetype(pfn_to_page(start_pfn), new_mt);
-
 	return pages_moved;
 }
 
@@ -2013,11 +2015,16 @@ static int move_freepages_block(struct zone *zone, struct page *page,
 				int old_mt, int new_mt)
 {
 	unsigned long start_pfn;
+	int res;
 
 	if (!prep_move_freepages_block(zone, page, &start_pfn, NULL, NULL))
 		return -1;
 
-	return __move_freepages_block(zone, start_pfn, old_mt, new_mt);
+	res = __move_freepages_block(zone, start_pfn, old_mt, new_mt);
+	set_pageblock_migratetype(pfn_to_page(start_pfn), new_mt);
+
+	return res;
+
 }
 
 #ifdef CONFIG_MEMORY_ISOLATION
@@ -2045,11 +2052,19 @@ static unsigned long find_large_buddy(unsigned long start_pfn)
 	return start_pfn;
 }
 
+static inline void toggle_pageblock_isolate(struct page *page, bool isolate)
+{
+	if (isolate)
+		set_pfnblock_bit(page, page_to_pfn(page), PB_migrate_isolate);
+	else
+		clear_pfnblock_bit(page, page_to_pfn(page), PB_migrate_isolate);
+}
+
 /**
- * move_freepages_block_isolate - move free pages in block for page isolation
+ * __move_freepages_block_isolate - move free pages in block for page isolation
  * @zone: the zone
  * @page: the pageblock page
- * @migratetype: migratetype to set on the pageblock
+ * @isolate: 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
@@ -2064,10 +2079,18 @@ 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_block_isolate(struct zone *zone,
+		struct page *page, bool isolate)
 {
 	unsigned long start_pfn, pfn;
+	int from_mt;
+	int to_mt;
+
+	if (isolate == get_pageblock_isolate(page)) {
+		VM_WARN_ONCE(1, "%s a pageblock that is already in that state",
+			     isolate ? "Isolate" : "Unisolate");
+		return false;
+	}
 
 	if (!prep_move_freepages_block(zone, page, &start_pfn, NULL, NULL))
 		return false;
@@ -2084,7 +2107,7 @@ 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);
+		toggle_pageblock_isolate(page, isolate);
 		split_large_buddy(zone, buddy, pfn, order, FPI_NONE);
 		return true;
 	}
@@ -2095,16 +2118,38 @@ 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);
+		toggle_pageblock_isolate(page, isolate);
 		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);
+	/* Use MIGRATETYPE_MASK to get non-isolate migratetype */
+	if (isolate) {
+		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);
+	toggle_pageblock_isolate(pfn_to_page(start_pfn), isolate);
+
 	return true;
 }
+
+bool pageblock_isolate_and_move_free_pages(struct zone *zone, struct page *page)
+{
+	return __move_freepages_block_isolate(zone, page, true);
+}
+
+bool pageblock_unisolate_and_move_free_pages(struct zone *zone, struct page *page)
+{
+	return __move_freepages_block_isolate(zone, page, false);
+}
+
 #endif /* CONFIG_MEMORY_ISOLATION */
 
 static void change_pageblock_range(struct page *pageblock_page,
@@ -2296,6 +2341,7 @@ try_to_claim_block(struct zone *zone, struct page *page,
 	if (free_pages + alike_pages >= (1 << (pageblock_order-1)) ||
 			page_group_by_mobility_disabled) {
 		__move_freepages_block(zone, start_pfn, block_type, start_type);
+		set_pageblock_migratetype(pfn_to_page(start_pfn), start_type);
 		return __rmqueue_smallest(zone, order, start_type);
 	}
 

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);
 	}
 }
 /*