ANDROID: vendor_hooks: add hook to balance_dirty_pages()

Add vendor hook in order to track which process cause dirty page write
back pressure.

Bug: 188096764
Change-Id: I890299c97d7a8cf791f20d16d8d53b4615679b9e
Signed-off-by: Yang Yang <yang.yang@vivo.com>

drivers/android/vendor_hooks.c

@@ -282,3 +282,4 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_tune_inactive_ratio);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_update_topology_flags_workfn);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_of_i2c_get_board_info);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_cgroup_attach);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_mm_dirty_limits);

include/trace/hooks/mm.h

@@ -71,6 +71,13 @@ struct slabinfo;
 DECLARE_HOOK(android_vh_cache_show,
 	TP_PROTO(struct seq_file *m, struct slabinfo *sinfo, struct kmem_cache *s),
 	TP_ARGS(m, sinfo, s));
+struct dirty_throttle_control;
+DECLARE_HOOK(android_vh_mm_dirty_limits,
+	TP_PROTO(struct dirty_throttle_control *const gdtc, bool strictlimit,
+		unsigned long dirty, unsigned long bg_thresh,
+		unsigned long nr_reclaimable, unsigned long pages_dirtied),
+	TP_ARGS(gdtc, strictlimit, dirty, bg_thresh,
+		nr_reclaimable, pages_dirtied));
 /* macro versions of hooks are no longer required */
 
 #endif /* _TRACE_HOOK_MM_H */

mm/page-writeback.c

@@ -42,6 +42,9 @@
 
 #include "internal.h"
 
+#undef CREATE_TRACE_POINT
+#include <trace/hooks/mm.h>
+
 /*
  * Sleep at most 200ms at a time in balance_dirty_pages().
  */
@@ -1625,6 +1628,9 @@ static void balance_dirty_pages(struct bdi_writeback *wb,
 			}
 		}
 
+		trace_android_vh_mm_dirty_limits(gdtc, strictlimit, dirty, bg_thresh,
+				nr_reclaimable, pages_dirtied);
+
 		/*
 		 * Throttle it only when the background writeback cannot
 		 * catch-up. This avoids (excessively) small writeouts