ANDROID: implement wrapper for reverse migration

Reverse migration is used to do the balancing the occupancy of memory
zones in a node in the system whose imabalance may be caused by
migration of pages to other zones by an operation, eg: hotremove and
then hotadding the same memory. In this case there is a lot of free
memory in newly hotadd memory which can be filled up by the previous
migrated pages(as part of offline/hotremove) thus may free up some
pressure in other zones of the node.

Upstream discussion: https://lore.kernel.org/all/ee78c83d-da9b-f6d1-4f66-934b7782acfb@codeaurora.org/

Port to ACK6.6: Fold in following simple fixes from ACK6.1:

commit d0652b3a8559 ("ANDROID: inline isolate_and_split_free_page")
commit 8a98feb47ec0 ("ANDROID: mm: compaction: fix isolate_and_split_free_page() redefinition")

Port to ACK6.12: Make below changes to patch:

1. Move isolate_and_split_free_page() into mm/page_alloc to be able to
   make use of split_free_pages() [1]. The @list argument is also
   now an array of lists based on page order on account of switching to the
   split_free_pages API.

2. isolate_lru_page is also deprecated. Hence isolate_anon_lru_page() is
   now using folio_isolate_lru() which is the folio equivalent.

[1] https://lore.kernel.org/all/20240814035451.773331-1-yuzhao@google.com/T/#u

Bug: 201263307
Signed-off-by: Charan Teja Reddy <quic_charante@quicinc.com>
Signed-off-by: Sukadev Bhattiprolu <quic_sukadev@quicinc.com>
Change-Id: Ib3137dab0db66ecf6858c4077dcadb9dfd0c6b1c

include/linux/mmzone.h

@@ -1622,6 +1622,18 @@ static inline struct pglist_data *NODE_DATA(int nid)
 extern struct pglist_data *first_online_pgdat(void);
 extern struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
 extern struct zone *next_zone(struct zone *zone);
+extern int isolate_anon_lru_page(struct page *page);
+
+#ifdef CONFIG_COMPACTION
+extern unsigned long isolate_and_split_free_page(struct page *page,
+			struct list_head *list);
+#else
+static inline unsigned long isolate_and_split_free_page(struct page *page,
+				struct list_head *list)
+{
+	return 0;
+}
+#endif /* CONFIG_COMPACTION */
 
 /**
  * for_each_online_pgdat - helper macro to iterate over all online nodes

mm/migrate.c

@@ -174,6 +174,7 @@ void putback_movable_pages(struct list_head *l)
 		}
 	}
 }
+EXPORT_SYMBOL_GPL(putback_movable_pages);
 
 /* Must be called with an elevated refcount on the non-hugetlb folio */
 bool isolate_folio_to_list(struct folio *folio, struct list_head *list)
@@ -2127,6 +2128,7 @@ out:
 
 	return rc_gather;
 }
+EXPORT_SYMBOL_GPL(migrate_pages);
 
 struct folio *alloc_migration_target(struct folio *src, unsigned long private)
 {

mm/page_alloc.c

@@ -452,6 +452,23 @@ unsigned long get_pfnblock_flags_mask(const struct page *page,
 }
 EXPORT_SYMBOL_GPL(get_pfnblock_flags_mask);
 
+int isolate_anon_lru_page(struct page *page)
+{
+	int ret;
+
+	if (!PageLRU(page) || !PageAnon(page))
+		return -EINVAL;
+
+	if (!get_page_unless_zero(page))
+		return -EINVAL;
+
+	ret = folio_isolate_lru(page_folio(page));
+	put_page(page);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(isolate_anon_lru_page);
+
 static __always_inline int get_pfnblock_migratetype(const struct page *page,
 					unsigned long pfn)
 {
@@ -6919,6 +6936,31 @@ static void split_free_pages(struct list_head *list)
 	}
 }
 
+#ifdef CONFIG_COMPACTION
+unsigned long isolate_and_split_free_page(struct page *page,
+		struct list_head *list)
+{
+	unsigned long isolated;
+	unsigned int order;
+
+	if (!PageBuddy(page))
+		return 0;
+
+	order = buddy_order(page);
+	isolated = __isolate_free_page(page, order);
+	if (!isolated)
+		return 0;
+
+	set_page_private(page, order);
+	list_add(&page->lru, &list[order]);
+
+	split_free_pages(list);
+
+	return isolated;
+}
+EXPORT_SYMBOL_GPL(isolate_and_split_free_page);
+#endif
+
 /**
  * alloc_contig_range() -- tries to allocate given range of pages
  * @start:	start PFN to allocate