ANDROID: add vendor hook for mapping_shrinkable

To control inode memory reclaim, add restricted vendor hook.

Bug: 347958166
Change-Id: Iefb9ef66c9fd5abae99adb1200263e4642f991cc
Signed-off-by: Minchan Kim <minchan@google.com>
(cherry picked from commit c53c09b1)
Signed-off-by: Dmitry Skiba <dskiba@google.com>

drivers/android/vendor_hooks.c

@@ -251,6 +251,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_binder_wait_for_work);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_madvise_pageout_begin);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_madvise_pageout_end);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_reclaim_folio_list);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_mapping_shrinkable);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_alloc_oem_binder_struct);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_binder_transaction_received);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_free_oem_binder_struct);

include/linux/pagemap.h

@@ -145,6 +145,8 @@ static inline bool mapping_empty(struct address_space *mapping)
 	return xa_empty(&mapping->i_pages);
 }
 
+extern void _trace_android_rvh_mapping_shrinkable(bool *shrinkable);
+
 /*
  * mapping_shrinkable - test if page cache state allows inode reclaim
  * @mapping: the page cache mapping
@@ -169,7 +171,11 @@ static inline bool mapping_empty(struct address_space *mapping)
 static inline bool mapping_shrinkable(struct address_space *mapping)
 {
 	void *head;
+	bool shrinkable = false;
 
+	_trace_android_rvh_mapping_shrinkable(&shrinkable);
+	if (shrinkable)
+		return true;
 	/*
 	 * On highmem systems, there could be lowmem pressure from the
 	 * inodes before there is highmem pressure from the page

include/trace/hooks/mm.h

@@ -143,6 +143,9 @@ DECLARE_RESTRICTED_HOOK(android_rvh_madvise_pageout_end,
 DECLARE_RESTRICTED_HOOK(android_rvh_reclaim_folio_list,
 			TP_PROTO(struct list_head *folio_list, void *private),
 			TP_ARGS(folio_list, private), 1);
+DECLARE_RESTRICTED_HOOK(android_rvh_mapping_shrinkable,
+			TP_PROTO(bool *shrinkable),
+			TP_ARGS(shrinkable), 1);
 DECLARE_HOOK(android_vh_meminfo_cache_adjust,
 	TP_PROTO(unsigned long *cached),
 	TP_ARGS(cached));

mm/filemap.c

@@ -67,6 +67,12 @@
 
 #include "swap.h"
 
+void _trace_android_rvh_mapping_shrinkable(bool *shrinkable)
+{
+	trace_android_rvh_mapping_shrinkable(shrinkable);
+}
+EXPORT_SYMBOL_GPL(_trace_android_rvh_mapping_shrinkable);
+
 /*
  * Shared mappings implemented 30.11.1994. It's not fully working yet,
  * though.