[PATCH v2] mm: Fix shmem THP counters on migration

From: Jan Glauber
Date: Mon Jun 19 2023 - 06:34:22 EST


The per node numa_stat values for shmem don't change on
page migration for THP:

grep shmem /sys/fs/cgroup/machine.slice/.../memory.numa_stat:

shmem N0=1092616192 N1=10485760
shmem_thp N0=1092616192 N1=10485760

migratepages 9181 0 1:

shmem N0=0 N1=1103101952
shmem_thp N0=1092616192 N1=10485760

Fix that by updating shmem_thp counters likewise to shmem counters
on page migration.

Signed-off-by: Jan Glauber <jglauber@xxxxxxxxxxxxxxxx>
---
mm/migrate.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/mm/migrate.c b/mm/migrate.c
index 01cac26a3127..d2ba786ea105 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -492,6 +492,11 @@ int folio_migrate_mapping(struct address_space *mapping,
if (folio_test_swapbacked(folio) && !folio_test_swapcache(folio)) {
__mod_lruvec_state(old_lruvec, NR_SHMEM, -nr);
__mod_lruvec_state(new_lruvec, NR_SHMEM, nr);
+
+ if (folio_test_transhuge(folio)) {
+ __mod_lruvec_state(old_lruvec, NR_SHMEM_THPS, -nr);
+ __mod_lruvec_state(new_lruvec, NR_SHMEM_THPS, nr);
+ }
}
#ifdef CONFIG_SWAP
if (folio_test_swapcache(folio)) {
--
2.25.1