ANDROID: vendor_hooks: account page-mapcount

Support five hooks as follows to account
the amount of multi-mapped pages in kernel:

- android_vh_show_mapcount_pages
- android_vh_do_traversal_lruvec
- android_vh_update_page_mapcount
- android_vh_add_page_to_lrulist
- android_vh_del_page_from_lrulist

Bug: 236578020
Signed-off-by: Peifeng Li <lipeifeng@oppo.com>
Change-Id: Ia2c7015aab442be7dbb496b8b630b9dff59ab935

mm/vmscan.c

@@ -1727,6 +1727,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 		case 0:
 			nr_taken += nr_pages;
 			nr_zone_taken[page_zonenum(page)] += nr_pages;
+			trace_android_vh_del_page_from_lrulist(page, false, lru);
 			list_move(&page->lru, dst);
 			break;
 
@@ -1901,6 +1902,7 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 		nr_pages = thp_nr_pages(page);
 		update_lru_size(lruvec, lru, page_zonenum(page), nr_pages);
 		list_move(&page->lru, &lruvec->lists[lru]);
+		trace_android_vh_add_page_to_lrulist(page, false, lru);
 
 		if (put_page_testzero(page)) {
 			__ClearPageLRU(page);