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From:   Liam Howlett <liam.howlett@oracle.com>
To:     "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Yu Zhao <yuzhao@google.com>
Subject: [PATCH v8 17/70] proc: remove VMA rbtree use from nommu
Thread-Topic: [PATCH v8 17/70] proc: remove VMA rbtree use from nommu
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Date:   Tue, 26 Apr 2022 15:06:32 +0000
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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

These users of the rbtree should probably have been walks of the linked
list, but convert them to use walks of the maple tree.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
 fs/proc/task_nommu.c | 45 +++++++++++++++++++++-----------------------
 1 file changed, 21 insertions(+), 24 deletions(-)

diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index a6d21fc0033c..2fd06f52b6a4 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -20,15 +20,13 @@
  */
 void task_mem(struct seq_file *m, struct mm_struct *mm)
 {
+	VMA_ITERATOR(vmi, mm, 0);
 	struct vm_area_struct *vma;
 	struct vm_region *region;
-	struct rb_node *p;
 	unsigned long bytes =3D 0, sbytes =3D 0, slack =3D 0, size;
-       =20
-	mmap_read_lock(mm);
-	for (p =3D rb_first(&mm->mm_rb); p; p =3D rb_next(p)) {
-		vma =3D rb_entry(p, struct vm_area_struct, vm_rb);
=20
+	mmap_read_lock(mm);
+	for_each_vma(vmi, vma) {
 		bytes +=3D kobjsize(vma);
=20
 		region =3D vma->vm_region;
@@ -82,15 +80,13 @@ void task_mem(struct seq_file *m, struct mm_struct *mm)
=20
 unsigned long task_vsize(struct mm_struct *mm)
 {
+	VMA_ITERATOR(vmi, mm, 0);
 	struct vm_area_struct *vma;
-	struct rb_node *p;
 	unsigned long vsize =3D 0;
=20
 	mmap_read_lock(mm);
-	for (p =3D rb_first(&mm->mm_rb); p; p =3D rb_next(p)) {
-		vma =3D rb_entry(p, struct vm_area_struct, vm_rb);
+	for_each_vma(vmi, vma)
 		vsize +=3D vma->vm_end - vma->vm_start;
-	}
 	mmap_read_unlock(mm);
 	return vsize;
 }
@@ -99,14 +95,13 @@ unsigned long task_statm(struct mm_struct *mm,
 			 unsigned long *shared, unsigned long *text,
 			 unsigned long *data, unsigned long *resident)
 {
+	VMA_ITERATOR(vmi, mm, 0);
 	struct vm_area_struct *vma;
 	struct vm_region *region;
-	struct rb_node *p;
 	unsigned long size =3D kobjsize(mm);
=20
 	mmap_read_lock(mm);
-	for (p =3D rb_first(&mm->mm_rb); p; p =3D rb_next(p)) {
-		vma =3D rb_entry(p, struct vm_area_struct, vm_rb);
+	for_each_vma(vmi, vma) {
 		size +=3D kobjsize(vma);
 		region =3D vma->vm_region;
 		if (region) {
@@ -190,17 +185,19 @@ static int nommu_vma_show(struct seq_file *m, struct =
vm_area_struct *vma)
  */
 static int show_map(struct seq_file *m, void *_p)
 {
-	struct rb_node *p =3D _p;
-
-	return nommu_vma_show(m, rb_entry(p, struct vm_area_struct, vm_rb));
+	return nommu_vma_show(m, _p);
 }
=20
 static void *m_start(struct seq_file *m, loff_t *pos)
 {
 	struct proc_maps_private *priv =3D m->private;
 	struct mm_struct *mm;
-	struct rb_node *p;
-	loff_t n =3D *pos;
+	struct vm_area_struct *vma;
+	unsigned long addr =3D *pos;
+
+	/* See m_next(). Zero at the start or after lseek. */
+	if (addr =3D=3D -1UL)
+		return NULL;
=20
 	/* pin the task and mm whilst we play with them */
 	priv->task =3D get_proc_task(priv->inode);
@@ -216,10 +213,10 @@ static void *m_start(struct seq_file *m, loff_t *pos)
 		return ERR_PTR(-EINTR);
 	}
=20
-	/* start from the Nth VMA */
-	for (p =3D rb_first(&mm->mm_rb); p; p =3D rb_next(p))
-		if (n-- =3D=3D 0)
-			return p;
+	/* start the next element from addr */
+	vma =3D find_vma(mm, addr);
+	if (vma)
+		return vma;
=20
 	mmap_read_unlock(mm);
 	mmput(mm);
@@ -242,10 +239,10 @@ static void m_stop(struct seq_file *m, void *_vml)
=20
 static void *m_next(struct seq_file *m, void *_p, loff_t *pos)
 {
-	struct rb_node *p =3D _p;
+	struct vm_area_struct *vma =3D _p;
=20
-	(*pos)++;
-	return p ? rb_next(p) : NULL;
+	*pos =3D vma->vm_end;
+	return find_vma(vma->vm_mm, vma->vm_end);
 }
=20
 static const struct seq_operations proc_pid_maps_ops =3D {
--=20
2.35.1