mm/oom_kill: use vma iterators instead of vma linked list

Use vma iterator in preparation of removing the linked list.

Link: https://lkml.kernel.org/r/20220906194824.2110408-62-Liam.Howlett@oracle.comSigned-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
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: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/oom_kill.c

@@ -513,6 +513,7 @@ bool __oom_reap_task_mm(struct mm_struct *mm)
 {
 	struct vm_area_struct *vma;
 	bool ret = true;
+	VMA_ITERATOR(vmi, mm, 0);
 
 	/*
 	 * Tell all users of get_user/copy_from_user etc... that the content
@@ -522,7 +523,7 @@ bool __oom_reap_task_mm(struct mm_struct *mm)
 	 */
 	set_bit(MMF_UNSTABLE, &mm->flags);
 
-	for (vma = mm->mmap ; vma; vma = vma->vm_next) {
+	for_each_vma(vmi, vma) {
 		if (vma->vm_flags & (VM_HUGETLB|VM_PFNMAP))
 			continue;