[PATCH v2 6/8] mm/huge_memory: remove stale NUMA hinting comment from follow_trans_huge_pmd()

David Hildenbrand
2023-08-01T12:50:32Z

That comment for pmd_protnone() was added in commit 2b4847e73004
("mm: numa: serialise parallel get_user_page against THP migration"), which
noted:

THP does not unmap pages due to a lack of support for migration
entries at a PMD level. This allows races with get_user_pages

Nowadays, we do have PMD migration entries, so the comment no longer
applies. Let's drop it.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
mm/huge_memory.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2cd3e5502180..0b709d2c46c6 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1467,7 +1467,6 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
return ERR_PTR(-EFAULT);

- /* Full NUMA hinting faults to serialise migration in fault paths */
if (pmd_protnone(*pmd) && !gup_can_follow_protnone(vma, flags))
return NULL;

--
2.41.0