[PATCH v2 52/61] mm/mempolicy: Use maple tree iterators instead of vma linked list

[Liam Howlett <liam.howlett@xxxxxxxxxx>]

From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>

Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
---
 mm/mempolicy.c | 41 +++++++++++++++++++++++++----------------
 1 file changed, 25 insertions(+), 16 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 9d3afa015fac..c8ded4c7dc93 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -377,10 +377,13 @@ void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new)
 void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
 {
 	struct vm_area_struct *vma;
+	MA_STATE(mas, &mm->mm_mt, 0, 0);
 
 	mmap_write_lock(mm);
-	for (vma = mm->mmap; vma; vma = vma->vm_next)
+	mas_lock(&mas);
+	mas_for_each(&mas, vma, ULONG_MAX)
 		mpol_rebind_policy(vma->vm_policy, new);
+	mas_unlock(&mas);
 	mmap_write_unlock(mm);
 }
 
@@ -652,7 +655,7 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma,
 static int queue_pages_test_walk(unsigned long start, unsigned long end,
 				struct mm_walk *walk)
 {
-	struct vm_area_struct *vma = walk->vma;
+	struct vm_area_struct *next, *vma = walk->vma;
 	struct queue_pages *qp = walk->private;
 	unsigned long endvma = vma->vm_end;
 	unsigned long flags = qp->flags;
@@ -667,9 +670,10 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
 			/* hole at head side of range */
 			return -EFAULT;
 	}
+	next = vma_next(vma->vm_mm, vma);
 	if (!(flags & MPOL_MF_DISCONTIG_OK) &&
 		((vma->vm_end < qp->end) &&
-		(!vma->vm_next || vma->vm_end < vma->vm_next->vm_start)))
+		(!next || vma->vm_end < next->vm_start)))
 		/* hole at middle or tail of range */
 		return -EFAULT;
 
@@ -783,28 +787,28 @@ static int vma_replace_policy(struct vm_area_struct *vma,
 static int mbind_range(struct mm_struct *mm, unsigned long start,
 		       unsigned long end, struct mempolicy *new_pol)
 {
-	struct vm_area_struct *next;
 	struct vm_area_struct *prev;
 	struct vm_area_struct *vma;
 	int err = 0;
 	pgoff_t pgoff;
 	unsigned long vmstart;
 	unsigned long vmend;
+	unsigned long index = start;
 
-	vma = find_vma(mm, start);
+	rcu_read_lock();
+	vma = find_vma_intersection(mm, start, end);
 	VM_BUG_ON(!vma);
 
-	prev = vma->vm_prev;
+	prev = vma_prev(mm, vma);
 	if (start > vma->vm_start)
 		prev = vma;
 
-	for (; vma && vma->vm_start < end; prev = vma, vma = next) {
-		next = vma->vm_next;
+	mt_for_each(&mm->mm_mt, vma, index, end - 1) {
 		vmstart = max(start, vma->vm_start);
 		vmend   = min(end, vma->vm_end);
 
 		if (mpol_equal(vma_policy(vma), new_pol))
-			continue;
+			goto next;
 
 		pgoff = vma->vm_pgoff +
 			((vmstart - vma->vm_start) >> PAGE_SHIFT);
@@ -813,7 +817,6 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
 				 new_pol, vma->vm_userfaultfd_ctx);
 		if (prev) {
 			vma = prev;
-			next = vma->vm_next;
 			if (mpol_equal(vma_policy(vma), new_pol))
 				continue;
 			/* vma_merge() joined vma && vma->next, case 8 */
@@ -829,13 +832,16 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
 			if (err)
 				goto out;
 		}
- replace:
+replace:
 		err = vma_replace_policy(vma, new_pol);
 		if (err)
 			goto out;
+next:
+		prev = vma;
 	}
 
- out:
+out:
+	rcu_read_unlock();
 	return err;
 }
 
@@ -1063,6 +1069,7 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
 			   int flags)
 {
 	nodemask_t nmask;
+	struct vm_area_struct *vma;
 	LIST_HEAD(pagelist);
 	int err = 0;
 	struct migration_target_control mtc = {
@@ -1078,8 +1085,9 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
 	 * need migration.  Between passing in the full user address
 	 * space range and MPOL_MF_DISCONTIG_OK, this call can not fail.
 	 */
+	vma = find_vma(mm, 0);
 	VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)));
-	queue_pages_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
+	queue_pages_range(mm, vma->vm_start, mm->task_size, &nmask,
 			flags | MPOL_MF_DISCONTIG_OK, &pagelist);
 
 	if (!list_empty(&pagelist)) {
@@ -1208,14 +1216,15 @@ static struct page *new_page(struct page *page, unsigned long start)
 {
 	struct vm_area_struct *vma;
 	unsigned long address;
+	MA_STATE(mas, &current->mm->mm_mt, start, start);
 
-	vma = find_vma(current->mm, start);
-	while (vma) {
+	rcu_read_lock();
+	mas_for_each(&mas, vma, ULONG_MAX) {
 		address = page_address_in_vma(page, vma);
 		if (address != -EFAULT)
 			break;
-		vma = vma->vm_next;
 	}
+	rcu_read_unlock();
 
 	if (PageHuge(page)) {
 		return alloc_huge_page_vma(page_hstate(compound_head(page)),
-- 
2.30.2