[PATCH 23/45] mm/mempolicy: Create queue_folios_pud to handle PUD-mapped hugetlb vmas

[Oscar Salvador <osalvador@xxxxxxx>]

Normal THP cannot be PUD-mapped (besides devmap), but hugetlb can, so create
queue_folios_pud in order to handle PUD-mapped hugetlb vmas.
Also implement is_pud_migration_entry and pud_folio, as they will be used in this patch.

Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
---
 include/linux/pgtable.h |  1 +
 include/linux/swapops.h | 12 ++++++++++++
 mm/mempolicy.c          | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 458e3cbc96b2..23d51fec81ac 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -51,6 +51,7 @@
 #endif
 
 #define pmd_folio(pmd) page_folio(pmd_page(pmd))
+#define pud_folio(pud) page_folio(pud_page(pud))
 
 /*
  * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD]
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 182957f0d013..a23900961d11 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -542,6 +542,18 @@ static inline bool is_pfn_swap_entry(swp_entry_t entry)
 
 struct page_vma_mapped_walk;
 
+#ifdef CONFIG_HUGETLB_PAGE
+static inline int is_pud_migration_entry(pud_t pud)
+{
+	return is_swap_pud(pud) && is_migration_entry(pud_to_swp_entry(pud));
+}
+#else
+static inline int is_pud_migration_entry(pud_t pud)
+{
+	return 0;
+}
+#endif
+
 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
 extern int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
 		struct page *page);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 5baf29da198c..93b14090d484 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -501,6 +501,37 @@ static inline bool queue_folio_required(struct folio *folio,
 	return node_isset(nid, *qp->nmask) == !(flags & MPOL_MF_INVERT);
 }
 
+static int queue_folios_pud(pud_t *pud, unsigned long addr, unsigned long end,
+			     struct mm_walk *walk)
+{
+	spinlock_t *ptl;
+	struct folio *folio;
+	struct vm_area_struct *vma = walk->vma;
+	struct queue_pages *qp = walk->private;
+
+	ptl = pud_huge_lock(pud, vma);
+	if (!ptl)
+		return 0;
+
+	if (unlikely(is_pud_migration_entry(*pud))) {
+		qp->nr_failed++;
+		goto out;
+	}
+	folio = pud_folio(*pud);
+	if (!queue_folio_required(folio, qp))
+		goto out;
+	if (!(qp->flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) ||
+	    !vma_migratable(walk->vma) ||
+	    !migrate_folio_add(folio, qp->pagelist, qp->flags, walk->vma, false))
+		qp->nr_failed++;
+
+	spin_unlock(ptl);
+out:
+	if (qp->nr_failed && strictly_unmovable(qp->flags))
+		return -EIO;
+	return 0;
+}
+
 static void queue_folios_pmd(pmd_t *pmd, struct mm_walk *walk)
 {
 	struct folio *folio;
@@ -730,6 +761,7 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
 
 static const struct mm_walk_ops queue_pages_walk_ops = {
 	.hugetlb_entry		= queue_folios_hugetlb,
+	.pud_entry		= queue_folios_pud,
 	.pmd_entry		= queue_folios_pte_range,
 	.test_walk		= queue_pages_test_walk,
 	.walk_lock		= PGWALK_RDLOCK,
-- 
2.26.2