[PATCH V2] mm/memcontrol: add per-memcg pgpgin/pswpin counter

[Jingxiang Zeng <jingxiangzeng.cas@gmail.com>]

From: Jingxiang Zeng <linuszeng@tencent.com>

In proactive memory reclamation scenarios, it is necessary to estimate the
pswpin and pswpout metrics of the cgroup to determine whether to continue
reclaiming anonymous pages in the current batch.  This patch will collect
these metrics and expose them.

Link: https://lkml.kernel.org/r/20240830082244.156923-1-jingxiangzeng.cas@gmail.com
Signed-off-by: Jingxiang Zeng <linuszeng@tencent.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/memcontrol.c | 2 ++
 mm/page_io.c    | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6efbfc9399d0..dbc1d43a5c4c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -418,6 +418,8 @@ static const unsigned int memcg_vm_event_stat[] = {
 	PGPGIN,
 	PGPGOUT,
 #endif
+	PSWPIN,
+	PSWPOUT,
 	PGSCAN_KSWAPD,
 	PGSCAN_DIRECT,
 	PGSCAN_KHUGEPAGED,
diff --git a/mm/page_io.c b/mm/page_io.c
index b6f1519d63b0..4bc77d1c6bfa 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -310,6 +310,7 @@ static inline void count_swpout_vm_event(struct folio *folio)
 	}
 	count_mthp_stat(folio_order(folio), MTHP_STAT_SWPOUT);
 #endif
+	count_memcg_folio_events(folio, PSWPOUT, folio_nr_pages(folio));
 	count_vm_events(PSWPOUT, folio_nr_pages(folio));
 }
 
@@ -505,6 +506,7 @@ static void sio_read_complete(struct kiocb *iocb, long ret)
 		for (p = 0; p < sio->pages; p++) {
 			struct folio *folio = page_folio(sio->bvec[p].bv_page);
 
+			count_memcg_folio_events(folio, PSWPIN, folio_nr_pages(folio));
 			folio_mark_uptodate(folio);
 			folio_unlock(folio);
 		}
@@ -588,6 +590,7 @@ static void swap_read_folio_bdev_sync(struct folio *folio,
 	 * attempt to access it in the page fault retry time check.
 	 */
 	get_task_struct(current);
+	count_memcg_folio_events(folio, PSWPIN, folio_nr_pages(folio));
 	count_vm_event(PSWPIN);
 	submit_bio_wait(&bio);
 	__end_swap_bio_read(&bio);
@@ -603,6 +606,7 @@ static void swap_read_folio_bdev_async(struct folio *folio,
 	bio->bi_iter.bi_sector = swap_folio_sector(folio);
 	bio->bi_end_io = end_swap_bio_read;
 	bio_add_folio_nofail(bio, folio, folio_size(folio), 0);
+	count_memcg_folio_events(folio, PSWPIN, folio_nr_pages(folio));
 	count_vm_event(PSWPIN);
 	submit_bio(bio);
 }
-- 
2.43.5