mm/mremap: use vmi version of vma_merge()

Use the vma iterator so that the iterator can be invalidated or updated to
avoid each caller doing so.

Link: https://lkml.kernel.org/r/20230120162650.984577-27-Liam.Howlett@oracle.comSigned-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/mremap.c

@@ -1018,6 +1018,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 			unsigned long extension_end = addr + new_len;
 			pgoff_t extension_pgoff = vma->vm_pgoff +
 				((extension_start - vma->vm_start) >> PAGE_SHIFT);
+			VMA_ITERATOR(vmi, mm, extension_start);
 
 			if (vma->vm_flags & VM_ACCOUNT) {
 				if (security_vm_enough_memory_mm(mm, pages)) {
@@ -1042,10 +1043,12 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 			 * when a vma would be actually removed due to a merge.
 			 */
 			if (!vma->vm_ops || !vma->vm_ops->close) {
-				vma = vma_merge(mm, vma, extension_start, extension_end,
-					vma->vm_flags, vma->anon_vma, vma->vm_file,
-					extension_pgoff, vma_policy(vma),
-					vma->vm_userfaultfd_ctx, anon_vma_name(vma));
+				vma = vmi_vma_merge(&vmi, mm, vma,
+				       extension_start, extension_end,
+				       vma->vm_flags, vma->anon_vma,
+				       vma->vm_file, extension_pgoff,
+				       vma_policy(vma), vma->vm_userfaultfd_ctx,
+				       anon_vma_name(vma));
 			} else if (vma_adjust(vma, vma->vm_start, addr + new_len,
 				   vma->vm_pgoff, NULL)) {
 				vma = NULL;