mm/vmscan: use vma iterator instead of vm_next

Use the vma iterator in in get_next_vma() instead of the linked list.

[yuzhao@google.com: mm/vmscan: use the proper VMA iterator]
  Link: https://lkml.kernel.org/r/Yx+QGOgHg1Wk8tGK@google.com
Link: https://lkml.kernel.org/r/20220906194824.2110408-68-Liam.Howlett@oracle.comSigned-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Yu Zhao <yuzhao@google.com>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan.c

@@ -3774,23 +3774,17 @@ static bool get_next_vma(unsigned long mask, unsigned long size, struct mm_walk
 {
 	unsigned long start = round_up(*vm_end, size);
 	unsigned long end = (start | ~mask) + 1;
+	VMA_ITERATOR(vmi, args->mm, start);
 
 	VM_WARN_ON_ONCE(mask & size);
 	VM_WARN_ON_ONCE((start & mask) != (*vm_start & mask));
 
-	while (args->vma) {
-		if (start >= args->vma->vm_end) {
-			args->vma = args->vma->vm_next;
-			continue;
-		}
-
+	for_each_vma(vmi, args->vma) {
 		if (end && end <= args->vma->vm_start)
 			return false;
 
-		if (should_skip_vma(args->vma->vm_start, args->vma->vm_end, args)) {
-			args->vma = args->vma->vm_next;
+		if (should_skip_vma(args->vma->vm_start, args->vma->vm_end, args))
 			continue;
-		}
 
 		*vm_start = max(start, args->vma->vm_start);
 		*vm_end = min(end - 1, args->vma->vm_end - 1) + 1;