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;