ANDROID: vendor hook to control pagevec flush

The pagevec batching causes lru_add_drain_all which is too expensive
sometimes. This patch adds a new vendor hook to drain the pagevec
immediately depending on the page's type.

Bug: 251881967
Signed-off-by: Minchan Kim <minchan@google.com>
Change-Id: Id17e14e69197993ddad511a40c96e51674c02834
Signed-off-by: Richard Chang <richardycc@google.com>
(cherry picked from commit 2f8253b7e6e563cc19cffa120c72f6f528664103)

drivers/android/vendor_hooks.c

@@ -278,3 +278,4 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_cma_alloc_adjust);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_enable_thermal_genl_check);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_mm_compaction_begin);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_mm_compaction_end);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_pagevec_drain);

include/trace/hooks/mm.h

@@ -77,6 +77,9 @@ DECLARE_HOOK(android_vh_mm_compaction_begin,
 DECLARE_HOOK(android_vh_mm_compaction_end,
 	TP_PROTO(struct compact_control *cc, long vendor_ret),
 	TP_ARGS(cc, vendor_ret));
+DECLARE_HOOK(android_vh_pagevec_drain,
+	TP_PROTO(struct page *page, bool *ret),
+	TP_ARGS(page, ret));
 struct mem_cgroup;
 DECLARE_HOOK(android_vh_mem_cgroup_alloc,
 	TP_PROTO(struct mem_cgroup *memcg),

mm/swap.c

@@ -43,6 +43,9 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/pagemap.h>
 
+#undef CREATE_TRACE_POINTS
+#include <trace/hooks/mm.h>
+
 /* How many pages do we try to swap or page in/out together? */
 int page_cluster;
 
@@ -223,6 +226,7 @@ static bool pagevec_add_and_need_flush(struct pagevec *pvec, struct page *page)
 			lru_cache_disabled())
 		ret = true;
 
+	trace_android_vh_pagevec_drain(page, &ret);
 	return ret;
 }