mm/memcontrol: add per-memcg pgpgin/pswpin counter

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/[email protected]
Signed-off-by: Jingxiang Zeng <[email protected]>
Acked-by: Nhat Pham <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Shakeel Butt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: linuszeng

mm/memcontrol-v1.c

@@ -2754,6 +2754,8 @@ static const char *const memcg1_stat_names[] = {
 static const unsigned int memcg1_events[] = {
 	PGPGIN,
 	PGPGOUT,
+	PSWPIN,
+	PSWPOUT,
 	PGFAULT,
 	PGMAJFAULT,
 };

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,

mm/page_io.c

@@ -290,6 +290,7 @@ 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));
 }
 
@@ -485,6 +486,7 @@ 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);
 		}
@@ -570,6 +572,7 @@ 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_events(PSWPIN, folio_nr_pages(folio));
 	submit_bio_wait(&bio);
 	__end_swap_bio_read(&bio);
@@ -585,6 +588,7 @@ 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_events(PSWPIN, folio_nr_pages(folio));
 	submit_bio(bio);
 }