mm/khugepaged: stop using vma linked list

Use vma iterator & find_vma() instead of vma linked list.

Link: https://lkml.kernel.org/r/20220906194824.2110408-53-Liam.Howlett@oracle.comSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
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: 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/huge_memory.c

@@ -2341,11 +2341,11 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
 	split_huge_pmd_if_needed(vma, end);
 
 	/*
-	 * If we're also updating the vma->vm_next->vm_start,
+	 * If we're also updating the next vma vm_start,
 	 * check if we need to split it.
 	 */
 	if (adjust_next > 0) {
-		struct vm_area_struct *next = vma->vm_next;
+		struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end);
 		unsigned long nstart = next->vm_start;
 		nstart += adjust_next;
 		split_huge_pmd_if_needed(next, nstart);

mm/khugepaged.c

@@ -2050,6 +2050,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
 	__releases(&khugepaged_mm_lock)
 	__acquires(&khugepaged_mm_lock)
 {
+	struct vma_iterator vmi;
 	struct mm_slot *mm_slot;
 	struct mm_struct *mm;
 	struct vm_area_struct *vma;
@@ -2078,11 +2079,13 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
 	vma = NULL;
 	if (unlikely(!mmap_read_trylock(mm)))
 		goto breakouterloop_mmap_lock;
-	if (likely(!hpage_collapse_test_exit(mm)))
-		vma = find_vma(mm, khugepaged_scan.address);
 
 	progress++;
-	for (; vma; vma = vma->vm_next) {
+	if (unlikely(hpage_collapse_test_exit(mm)))
+		goto breakouterloop;
+
+	vma_iter_init(&vmi, mm, khugepaged_scan.address);
+	for_each_vma(vmi, vma) {
 		unsigned long hstart, hend;
 
 		cond_resched();