As the legacy lru provides, the mglru needs some trace events for
debugging.  Let's reuse following legacy events for the mglru.

  trace_mm_vmscan_lru_isolate
  trace_mm_vmscan_lru_shrink_inactive

Here's an example
  mm_vmscan_lru_isolate: classzone=2 order=0 nr_requested=4096 nr_scanned=64 nr_skipped=0 nr_taken=64 lru=inactive_file
  mm_vmscan_lru_shrink_inactive: nid=0 nr_scanned=64 nr_reclaimed=63 nr_dirty=0 nr_writeback=0 nr_congested=0 nr_immediate=0 nr_activate_anon=0 nr_activate_file=1 nr_ref_keep=0 nr_unmap_fail=0 priority=2 flags=RECLAIM_WB_FILE|RECLAIM_WB_ASYNC

Link: https://lkml.kernel.org/r/20231003114155.21869-1-jaewon31.kim@samsung.comSigned-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Acked-by: Yu Zhao <yuzhao@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: T.J. Mercier <tjmercier@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>