mm: stop storing migration_ops in page->mapping

...  instead, look them up statically based on the page type.  Maybe in
the future we want a registration interface?  At least for now, it can be
easily handled using the two page types that actually support page
migration.

The remaining usage of page->mapping is to flag such pages as actually
being movable (having movable_ops), which we will change next.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Reviewed-by: Zi Yan <[email protected]>
Reviewed-by: Lorenzo Stoakes <[email protected]>
Reviewed-by: Harry Yoo <[email protected]>
Cc: Alistair Popple <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Brendan Jackman <[email protected]>
Cc: Byungchul Park <[email protected]>
Cc: Chengming Zhou <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Eugenio Pé rez <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Gregory Price <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Jerrin Shaji George <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Joshua Hahn <[email protected]>
Cc: Liam Howlett <[email protected]>
Cc: Madhavan Srinivasan <[email protected]>
Cc: Mathew Brost <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Qi Zheng <[email protected]>
Cc: Rakie Kim <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Cc: xu xin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

include/linux/balloon_compaction.h

@@ -92,7 +92,7 @@ static inline void balloon_page_insert(struct balloon_dev_info *balloon,
 				       struct page *page)
 {
 	__SetPageOffline(page);
-	__SetPageMovable(page, &balloon_mops);
+	__SetPageMovable(page);
 	set_page_private(page, (unsigned long)balloon);
 	list_add(&page->lru, &balloon->pages);
 }

include/linux/migrate.h

@@ -104,23 +104,13 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
 #endif /* CONFIG_MIGRATION */
 
 #ifdef CONFIG_COMPACTION
-void __SetPageMovable(struct page *page, const struct movable_operations *ops);
+void __SetPageMovable(struct page *page);
 #else
-static inline void __SetPageMovable(struct page *page,
-		const struct movable_operations *ops)
+static inline void __SetPageMovable(struct page *page)
 {
 }
 #endif
 
-static inline
-const struct movable_operations *page_movable_ops(struct page *page)
-{
-	VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(page), page);
-
-	return (const struct movable_operations *)
-		((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE);
-}
-
 #ifdef CONFIG_NUMA_BALANCING
 int migrate_misplaced_folio_prepare(struct folio *folio,
 		struct vm_area_struct *vma, int node);

include/linux/zsmalloc.h

@@ -46,4 +46,6 @@ void zs_obj_read_end(struct zs_pool *pool, unsigned long handle,
 void zs_obj_write(struct zs_pool *pool, unsigned long handle,
 		  void *handle_mem, size_t mem_len);
 
+extern const struct movable_operations zsmalloc_mops;
+
 #endif

mm/balloon_compaction.c

@@ -253,6 +253,5 @@ const struct movable_operations balloon_mops = {
 	.isolate_page = balloon_page_isolate,
 	.putback_page = balloon_page_putback,
 };
-EXPORT_SYMBOL_GPL(balloon_mops);
 
 #endif /* CONFIG_BALLOON_COMPACTION */

mm/compaction.c

@@ -114,11 +114,10 @@ static unsigned long release_free_list(struct list_head *freepages)
 }
 
 #ifdef CONFIG_COMPACTION
-void __SetPageMovable(struct page *page, const struct movable_operations *mops)
+void __SetPageMovable(struct page *page)
 {
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	VM_BUG_ON_PAGE((unsigned long)mops & PAGE_MAPPING_MOVABLE, page);
-	page->mapping = (void *)((unsigned long)mops | PAGE_MAPPING_MOVABLE);
+	page->mapping = (void *)(PAGE_MAPPING_MOVABLE);
 }
 EXPORT_SYMBOL(__SetPageMovable);
 

mm/migrate.c

@@ -43,6 +43,8 @@
 #include <linux/sched/sysctl.h>
 #include <linux/memory-tiers.h>
 #include <linux/pagewalk.h>
+#include <linux/balloon_compaction.h>
+#include <linux/zsmalloc.h>
 
 #include <asm/tlbflush.h>
 
@@ -51,6 +53,27 @@
 #include "internal.h"
 #include "swap.h"
 
+static const struct movable_operations *page_movable_ops(struct page *page)
+{
+	VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(page), page);
+
+	/*
+	 * If we enable page migration for a page of a certain type by marking
+	 * it as movable, the page type must be sticky until the page gets freed
+	 * back to the buddy.
+	 */
+#ifdef CONFIG_BALLOON_COMPACTION
+	if (PageOffline(page))
+		/* Only balloon compaction sets PageOffline pages movable. */
+		return &balloon_mops;
+#endif /* CONFIG_BALLOON_COMPACTION */
+#if defined(CONFIG_ZSMALLOC) && defined(CONFIG_COMPACTION)
+	if (PageZsmalloc(page))
+		return &zsmalloc_mops;
+#endif /* defined(CONFIG_ZSMALLOC) && defined(CONFIG_COMPACTION) */
+	return NULL;
+}
+
 /**
  * isolate_movable_ops_page - isolate a movable_ops page for migration
  * @page: The page.

mm/zpdesc.h

@@ -152,10 +152,9 @@ static inline struct zpdesc *pfn_zpdesc(unsigned long pfn)
 	return page_zpdesc(pfn_to_page(pfn));
 }
 
-static inline void __zpdesc_set_movable(struct zpdesc *zpdesc,
-					const struct movable_operations *mops)
+static inline void __zpdesc_set_movable(struct zpdesc *zpdesc)
 {
-	__SetPageMovable(zpdesc_page(zpdesc), mops);
+	__SetPageMovable(zpdesc_page(zpdesc));
 }
 
 static inline void __zpdesc_set_zsmalloc(struct zpdesc *zpdesc)

mm/zsmalloc.c

@@ -1685,8 +1685,6 @@ static void lock_zspage(struct zspage *zspage)
 
 #ifdef CONFIG_COMPACTION
 
-static const struct movable_operations zsmalloc_mops;
-
 static void replace_sub_page(struct size_class *class, struct zspage *zspage,
 				struct zpdesc *newzpdesc, struct zpdesc *oldzpdesc)
 {
@@ -1709,7 +1707,7 @@ static void replace_sub_page(struct size_class *class, struct zspage *zspage,
 	set_first_obj_offset(newzpdesc, first_obj_offset);
 	if (unlikely(ZsHugePage(zspage)))
 		newzpdesc->handle = oldzpdesc->handle;
-	__zpdesc_set_movable(newzpdesc, &zsmalloc_mops);
+	__zpdesc_set_movable(newzpdesc);
 }
 
 static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
@@ -1819,7 +1817,7 @@ static void zs_page_putback(struct page *page)
 {
 }
 
-static const struct movable_operations zsmalloc_mops = {
+const struct movable_operations zsmalloc_mops = {
 	.isolate_page = zs_page_isolate,
 	.migrate_page = zs_page_migrate,
 	.putback_page = zs_page_putback,
@@ -1882,7 +1880,7 @@ static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage)
 
 	do {
 		WARN_ON(!zpdesc_trylock(zpdesc));
-		__zpdesc_set_movable(zpdesc, &zsmalloc_mops);
+		__zpdesc_set_movable(zpdesc);
 		zpdesc_unlock(zpdesc);
 	} while ((zpdesc = get_next_zpdesc(zpdesc)) != NULL);
 }