On Tue, Jul 07, 2026 at 09:36:17PM +0800, Wandun wrote:
<snip>

quoted

diff --git a/mm/mlock.c b/mm/mlock.c
index ac65de40b22b..f56c685533f5 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c

<snip>

quoted

+static int mlock_collect_migratable_pte_range(pmd_t *pmd, unsigned long addr,
+			unsigned long end, struct mm_walk *walk)
+{
+	struct vm_area_struct *vma = walk->vma;
+	struct list_head *folio_list = walk->private;
+	spinlock_t *ptl;
+	pte_t *start_pte, *pte;
+	pte_t ptent;
+	struct folio *folio;
+	unsigned int step = 1;
+
+	if (!(vma->vm_flags & VM_LOCKED))
+		return 0;
+
+	ptl = pmd_trans_huge_lock(pmd, vma);
+	if (ptl) {
+		if (!pmd_present(*pmd)) {
+			if (unlikely(softleaf_is_migration(softleaf_from_pmd(*pmd)))) {
+				spin_unlock(ptl);
+				pmd_migration_entry_wait(vma->vm_mm, pmd);
+				walk->action = ACTION_AGAIN;
+				return 0;
+			}
+			goto out;
+		}
+		if (is_huge_zero_pmd(*pmd))
+			goto out;
+		folio = pmd_folio(*pmd);
+		if (folio_is_zone_device(folio))
+			goto out;
+		if (is_migrate_cma_page(&folio->page))
+			isolate_folio_to_list(folio, folio_list);
+		goto out;
+	}
+
+	start_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	if (!start_pte) {
+		walk->action = ACTION_AGAIN;
+		return 0;
+	}
+
+	for (pte = start_pte; addr != end; pte += step, addr += step * PAGE_SIZE) {
+		step = 1;
+		ptent = ptep_get(pte);
+		if (!pte_present(ptent)) {
+			if (unlikely(softleaf_is_migration(softleaf_from_pte(ptent)))) {
+				pte_unmap_unlock(start_pte, ptl);
+				migration_entry_wait(vma->vm_mm, pmd, addr);
+				walk->action = ACTION_AGAIN;
+				return 0;
+			}
+			continue;
+		}
+		folio = vm_normal_folio(vma, addr, ptent);
+		if (!folio || folio_is_zone_device(folio))
+			continue;
+		step = folio_mlock_step(folio, pte, addr, end);
+		if (is_migrate_cma_page(&folio->page))

Here should be, sorry about this.
	if (!is_migrate_cma_page(&folio->page))
		continue;

But above you do the:

		if (is_migrate_cma_page(&folio->page))
			isolate_folio_to_list(folio, folio_list);

Pattern :) so these should be consistent. But you're copy/pasting and need to
not do that so it's kind of by the by.

Anyway, yes I assumed you meant this. But see the main review, I am not really a
fan of the implementation, overall.

Best regards
Wandun

Thanks, Lorenzo