From 0e1cb2770027dfe01d429e0318377a997fd57dd0 Mon Sep 17 00:00:00 2001
From: Bing Han <bing.han@transsion.com>
Date: Mon, 11 Jul 2022 17:12:21 +0800
Subject: [PATCH] ANDROID: vendor_hook: Add hook in shmem_writepage()

Add vendor hook android_vh_set_shmem_page_flag in shmem_writepage to
set a flag in page_ext, which indicates that this page is a shmem page,
to be used in android_vh_get_swap_page. The shared page should not be
reclaimed to the extended memory, ie, the specified swap location.

Bug: 234214858
Signed-off-by: Bing Han <bing.han@transsion.com>
Change-Id: I33a9007c88b4d8aab3da044c8a05eb45d7e74f3a
---
 drivers/android/vendor_hooks.c | 1 +
 include/trace/hooks/mm.h       | 3 +++
 mm/shmem.c                     | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/drivers/android/vendor_hooks.c b/drivers/android/vendor_hooks.c
index a6c589b266da..c43d1cd06928 100644
--- a/drivers/android/vendor_hooks.c
+++ b/drivers/android/vendor_hooks.c
@@ -430,3 +430,4 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_init_swap_info_struct);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_si_swapinfo);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_alloc_si);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_free_pages);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_set_shmem_page_flag);
diff --git a/include/trace/hooks/mm.h b/include/trace/hooks/mm.h
index 91d9172c6b4a..3f2784c6a0e5 100644
--- a/include/trace/hooks/mm.h
+++ b/include/trace/hooks/mm.h
@@ -215,6 +215,9 @@ DECLARE_HOOK(android_vh_alloc_si,
 DECLARE_HOOK(android_vh_free_pages,
 	TP_PROTO(struct page *page, unsigned int order),
 	TP_ARGS(page, order));
+DECLARE_HOOK(android_vh_set_shmem_page_flag,
+	TP_PROTO(struct page *page),
+	TP_ARGS(page));
 /* macro versions of hooks are no longer required */
 
 #endif /* _TRACE_HOOK_MM_H */
diff --git a/mm/shmem.c b/mm/shmem.c
index 0ed98d632eaa..768c91896036 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -46,6 +46,7 @@
 
 #undef CREATE_TRACE_POINTS
 #include <trace/hooks/shmem_fs.h>
+#include <trace/hooks/mm.h>
 
 static struct vfsmount *shm_mnt;
 
@@ -1430,6 +1431,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 		SetPageUptodate(page);
 	}
 
+	trace_android_vh_set_shmem_page_flag(page);
 	swap = get_swap_page(page);
 	if (!swap.val)
 		goto redirty;