Unmapped pagecache presently cannot be promoted off of lower tiers,
even if they are being accessed by read/write calls. Enable migration
in mark_folio_accessed if a given folio presently resides on a lower
tier of memory.
Suggested-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Gregory Price <gourry@xxxxxxxxxx>
---
mm/swap.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/mm/swap.c b/mm/swap.c
index 9caf6b017cf0..08f76d748e29 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -37,6 +37,9 @@
#include <linux/page_idle.h>
#include <linux/local_lock.h>
#include <linux/buffer_head.h>
+#include <linux/sched/sysctl.h>
+#include <linux/memory-tiers.h>
+#include <linux/migrate.h>
#include "internal.h"
@@ -463,9 +466,26 @@ static void folio_inc_refs(struct folio *folio)
*
* When a newly allocated folio is not yet visible, so safe for non-atomic ops,
* __folio_set_referenced() may be substituted for folio_mark_accessed().
+ *
+ * This call may also attempt to migrate the folio memory to the local node
+ * if it presently resides on a lower memory tier.
*/
void folio_mark_accessed(struct folio *folio)
{
+ int nid = folio_nid(folio);
+
+ /* If folio is on lower tier, try to promote to local node */
+ if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
+ (nid == NUMA_NO_NODE || !node_is_toptier(nid))) {
+ int flags;
+
+ nid = numa_migrate_prep(folio, NULL, 0, nid, &flags);
+ if ((nid != NUMA_NO_NODE) &&
+ !migrate_misplaced_folio_prepare(folio, NULL, nid)) {
+ migrate_misplaced_folio(folio, nid);
+ }
+ }
+
if (lru_gen_enabled()) {
folio_inc_refs(folio);
return;
--
2.43.0
