[PATCH v5 08/36] mm/mempolicy: skip private node folios when queueing for migration

[Gregory Price]

Private nodes are already kept out of policy nodemasks (only N_MEMORY
nodes are allowed), but an mbind(MPOL_MF_MOVE) walk can still encounter a
private-node folio in the range.  Skip such folios so mempolicy-driven
migration never moves private-node memory.

We already do this for ZONE_DEVICE folios - use the same filter points
for ZONE_DEVICE (with an additional point for large pages).

Signed-off-by: Gregory Price <gourry@xxxxxxxxxx>
---
 mm/mempolicy.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 5720f7f54d942..8e8763f6e5f5b 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -111,6 +111,7 @@
 #include <linux/mmu_notifier.h>
 #include <linux/printk.h>
 #include <linux/leafops.h>
+#include <linux/node_private.h>
 #include <linux/gcd.h>
 
 #include <asm/tlbflush.h>
@@ -668,6 +669,8 @@ static void queue_folios_pmd(pmd_t *pmd, struct mm_walk *walk)
 	}
 	if (!queue_folio_required(folio, qp))
 		return;
+	if (folio_is_private_node(folio))
+		return;
 	if (!(qp->flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) ||
 	    !vma_migratable(walk->vma) ||
 	    !migrate_folio_add(folio, qp->pagelist, qp->flags))
@@ -722,7 +725,7 @@ static int queue_folios_pte_range(pmd_t *pmd, unsigned long addr,
 			continue;
 		}
 		folio = vm_normal_folio(vma, addr, ptent);
-		if (!folio || folio_is_zone_device(folio))
+		if (!folio || folio_is_private_managed(folio))
 			continue;
 		if (folio_test_large(folio) && max_nr != 1)
 			nr = folio_pte_batch(folio, pte, ptent, max_nr);
@@ -797,6 +800,8 @@ static int queue_folios_hugetlb(pte_t *pte, unsigned long hmask,
 	folio = pfn_folio(pte_pfn(ptep));
 	if (!queue_folio_required(folio, qp))
 		goto unlock;
+	if (folio_is_private_node(folio))
+		goto unlock;
 	if (!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) ||
 	    !vma_migratable(walk->vma)) {
 		qp->nr_failed++;
-- 
2.53.0-Meta