From e56f8712cffc38406771a6a0c658ed4227559265 Mon Sep 17 00:00:00 2001
From: Peifeng Li <lipeifeng@oppo.com>
Date: Thu, 23 Jun 2022 15:15:46 +0800
Subject: [PATCH] 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
---
 drivers/android/vendor_hooks.c |  2 ++
 include/trace/hooks/mm.h       |  6 ++++++
 mm/swap.c                      |  1 +
 mm/vmscan.c                    | 13 +++++++++++++
 4 files changed, 22 insertions(+)

diff --git a/drivers/android/vendor_hooks.c b/drivers/android/vendor_hooks.c
index ae0a674fe6f7..d7fab5cb876d 100644
--- a/drivers/android/vendor_hooks.c
+++ b/drivers/android/vendor_hooks.c
@@ -398,6 +398,8 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_mmap_region);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_update_page_mapcount);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_add_page_to_lrulist);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_del_page_from_lrulist);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_page_should_be_protected);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_mark_page_accessed);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_try_to_unmap_one);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_mem_cgroup_id_remove);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_mem_cgroup_css_offline);
diff --git a/include/trace/hooks/mm.h b/include/trace/hooks/mm.h
index 68d792378b50..495f66d0f926 100644
--- a/include/trace/hooks/mm.h
+++ b/include/trace/hooks/mm.h
@@ -169,6 +169,12 @@ DECLARE_HOOK(android_vh_show_mapcount_pages,
 DECLARE_HOOK(android_vh_do_traversal_lruvec,
 	TP_PROTO(struct lruvec *lruvec),
 	TP_ARGS(lruvec));
+DECLARE_HOOK(android_vh_page_should_be_protected,
+	TP_PROTO(struct page *page, bool *should_protect),
+	TP_ARGS(page, should_protect));
+DECLARE_HOOK(android_vh_mark_page_accessed,
+	TP_PROTO(struct page *page),
+	TP_ARGS(page));
 DECLARE_HOOK(android_vh_cma_drain_all_pages_bypass,
 	TP_PROTO(unsigned int migratetype, bool *bypass),
 	TP_ARGS(migratetype, bypass));
diff --git a/mm/swap.c b/mm/swap.c
index abf445bd7721..16b2bc48211e 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -437,6 +437,7 @@ void mark_page_accessed(struct page *page)
 {
 	page = compound_head(page);
 
+	trace_android_vh_mark_page_accessed(page);
 	if (!PageReferenced(page)) {
 		SetPageReferenced(page);
 	} else if (PageUnevictable(page)) {
diff --git a/mm/vmscan.c b/mm/vmscan.c
index fef55a9ed60f..22ab1afed87f 100644
--- a/mm/vmscan.c
+++ b/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;