ANDROID: vendor_hooks: protect multi-mapcount pages in kernel

Support two hooks as follows to protect multi-mapcount pages in kernel:

- trace_android_vh_page_should_be_protect
- trace_android_vh_mapped_page_try_sorthead

Bug: 236578020
Signed-off-by: Peifeng Li <lipeifeng@oppo.com>
Change-Id: I688aceabf17d9de2feac7c3ad7144d307de6ef29

mm/vmscan.c

@@ -1020,6 +1020,11 @@ static enum page_references page_check_references(struct page *page,
 {
 	int referenced_ptes, referenced_page;
 	unsigned long vm_flags;
+	bool should_protect = false;
+
+	trace_android_vh_page_should_be_protected(page, &should_protect);
+	if (unlikely(should_protect))
+		return PAGEREF_ACTIVATE;
 
 	referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup,
 					  &vm_flags);
@@ -2057,6 +2062,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
 	int file = is_file_lru(lru);
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
 	bool bypass = false;
+	bool should_protect = false;
 
 	lru_add_drain();
 
@@ -2091,6 +2097,13 @@ static void shrink_active_list(unsigned long nr_to_scan,
 			}
 		}
 
+		trace_android_vh_page_should_be_protected(page, &should_protect);
+		if (unlikely(should_protect)) {
+			nr_rotated += thp_nr_pages(page);
+			list_add(&page->lru, &l_active);
+			continue;
+		}
+
 		trace_android_vh_page_referenced_check_bypass(page, nr_to_scan, lru, &bypass);
 		if (bypass)
 			goto skip_page_referenced;