[PATCH] mm/migrate_device: Cleanup up PMD Checks and warnings

Sunny Patel
2026-04-14T14:13:57Z

Remove the odd VM_WARN_ON_FOLIO(!folio, folio) usage and replace it
with a simpler VM_WARN_ON_ONCE(!folio) check.

Drop the redundant VM_WARN_ON_ONCE(!pmd_none(*pmdp) &&
!is_huge_zero_pmd(*pmdp)).

Refactor the PMD checks to use pmd_present(), making the control flow
clearer and avoiding duplicate condition checks.

Signed-off-by: Sunny Patel <nueralspacetech@gmail.com>
---
mm/migrate_device.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 8079676c8f1f..fe1c1999aa2d 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -807,8 +807,7 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
bool flush = false;
unsigned long i;

- VM_WARN_ON_FOLIO(!folio, folio);
- VM_WARN_ON_ONCE(!pmd_none(*pmdp) && !is_huge_zero_pmd(*pmdp));
+ VM_WARN_ON_ONCE(!folio);

if (!thp_vma_suitable_order(vma, addr, HPAGE_PMD_ORDER))
return -EINVAL;
@@ -865,12 +864,13 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
if (userfaultfd_missing(vma))
goto unlock_abort;

- if (!pmd_none(*pmdp)) {
+ if (pmd_present(*pmdp)) {
if (!is_huge_zero_pmd(*pmdp))
goto unlock_abort;
flush = true;
- } else if (!pmd_none(*pmdp))
+ } else if (!pmd_none(*pmdp)) {
goto unlock_abort;
+ }

add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);
--
2.43.0