[PATCH 5.10 125/199] mm: fix numa stats for thp migration

[Greg Kroah-Hartman]

From: Shakeel Butt <shakeelb@xxxxxxxxxx>

commit 5c447d274f3746fbed6e695e7b9a2d7bd8b31b71 upstream.

Currently the kernel is not correctly updating the numa stats for
NR_FILE_PAGES and NR_SHMEM on THP migration.  Fix that.

For NR_FILE_DIRTY and NR_ZONE_WRITE_PENDING, although at the moment
there is no need to handle THP migration as kernel still does not have
write support for file THP but to be more future proof, this patch adds
the THP support for those stats as well.

Link: https://lkml.kernel.org/r/20210108155813.2914586-2-shakeelb@xxxxxxxxxx
Fixes: e71769ae52609 ("mm: enable thp migration for shmem thp")
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Acked-by: Yang Shi <shy828301@xxxxxxxxx>
Reviewed-by: Roman Gushchin <guro@xxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 mm/migrate.c |   23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -406,6 +406,7 @@ int migrate_page_move_mapping(struct add
 	struct zone *oldzone, *newzone;
 	int dirty;
 	int expected_count = expected_page_refs(mapping, page) + extra_count;
+	int nr = thp_nr_pages(page);
 
 	if (!mapping) {
 		/* Anonymous page without mapping */
@@ -441,7 +442,7 @@ int migrate_page_move_mapping(struct add
 	 */
 	newpage->index = page->index;
 	newpage->mapping = page->mapping;
-	page_ref_add(newpage, thp_nr_pages(page)); /* add cache reference */
+	page_ref_add(newpage, nr); /* add cache reference */
 	if (PageSwapBacked(page)) {
 		__SetPageSwapBacked(newpage);
 		if (PageSwapCache(page)) {
@@ -463,7 +464,7 @@ int migrate_page_move_mapping(struct add
 	if (PageTransHuge(page)) {
 		int i;
 
-		for (i = 1; i < HPAGE_PMD_NR; i++) {
+		for (i = 1; i < nr; i++) {
 			xas_next(&xas);
 			xas_store(&xas, newpage);
 		}
@@ -474,7 +475,7 @@ int migrate_page_move_mapping(struct add
 	 * to one less reference.
 	 * We know this isn't the last reference.
 	 */
-	page_ref_unfreeze(page, expected_count - thp_nr_pages(page));
+	page_ref_unfreeze(page, expected_count - nr);
 
 	xas_unlock(&xas);
 	/* Leave irq disabled to prevent preemption while updating stats */
@@ -497,17 +498,17 @@ int migrate_page_move_mapping(struct add
 		old_lruvec = mem_cgroup_lruvec(memcg, oldzone->zone_pgdat);
 		new_lruvec = mem_cgroup_lruvec(memcg, newzone->zone_pgdat);
 
-		__dec_lruvec_state(old_lruvec, NR_FILE_PAGES);
-		__inc_lruvec_state(new_lruvec, NR_FILE_PAGES);
+		__mod_lruvec_state(old_lruvec, NR_FILE_PAGES, -nr);
+		__mod_lruvec_state(new_lruvec, NR_FILE_PAGES, nr);
 		if (PageSwapBacked(page) && !PageSwapCache(page)) {
-			__dec_lruvec_state(old_lruvec, NR_SHMEM);
-			__inc_lruvec_state(new_lruvec, NR_SHMEM);
+			__mod_lruvec_state(old_lruvec, NR_SHMEM, -nr);
+			__mod_lruvec_state(new_lruvec, NR_SHMEM, nr);
 		}
 		if (dirty && mapping_can_writeback(mapping)) {
-			__dec_lruvec_state(old_lruvec, NR_FILE_DIRTY);
-			__dec_zone_state(oldzone, NR_ZONE_WRITE_PENDING);
-			__inc_lruvec_state(new_lruvec, NR_FILE_DIRTY);
-			__inc_zone_state(newzone, NR_ZONE_WRITE_PENDING);
+			__mod_lruvec_state(old_lruvec, NR_FILE_DIRTY, -nr);
+			__mod_zone_page_state(oldzone, NR_ZONE_WRITE_PENDING, -nr);
+			__mod_lruvec_state(new_lruvec, NR_FILE_DIRTY, nr);
+			__mod_zone_page_state(newzone, NR_ZONE_WRITE_PENDING, nr);
 		}
 	}
 	local_irq_enable();