mm: handle swap and NUMA PTE faults under the VMA lock

Move the FAULT_FLAG_VMA_LOCK check down in handle_pte_fault().  This is
probably not a huge win in its own right, but is a nicely separable bit
from the next patch.

Link: https://lkml.kernel.org/r/20230724185410.1124082-10-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Punit Agrawal <punit.agrawal@bytedance.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory.c

@@ -4979,18 +4979,18 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
 	if (!vmf->pte)
 		return do_pte_missing(vmf);
 
-	if ((vmf->flags & FAULT_FLAG_VMA_LOCK) && !vma_is_anonymous(vmf->vma)) {
-		pte_unmap(vmf->pte);
-		vma_end_read(vmf->vma);
-		return VM_FAULT_RETRY;
-	}
-
 	if (!pte_present(vmf->orig_pte))
 		return do_swap_page(vmf);
 
 	if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
 		return do_numa_page(vmf);
 
+	if ((vmf->flags & FAULT_FLAG_VMA_LOCK) && !vma_is_anonymous(vmf->vma)) {
+		pte_unmap(vmf->pte);
+		vma_end_read(vmf->vma);
+		return VM_FAULT_RETRY;
+	}
+
 	spin_lock(vmf->ptl);
 	entry = vmf->orig_pte;
 	if (unlikely(!pte_same(ptep_get(vmf->pte), entry))) {