proc: inline vma_stop into m_stop

Instead of calling vma_stop() from m_start() and m_next(), do its work
in m_stop().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200317193201.9924-1-adobriyan@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/task_mmu.c

@@ -123,15 +123,6 @@ static void release_task_mempolicy(struct proc_maps_private *priv)
 }
 #endif
 
-static void vma_stop(struct proc_maps_private *priv)
-{
-	struct mm_struct *mm = priv->mm;
-
-	release_task_mempolicy(priv);
-	up_read(&mm->mmap_sem);
-	mmput(mm);
-}
-
 static struct vm_area_struct *
 m_next_vma(struct proc_maps_private *priv, struct vm_area_struct *vma)
 {
@@ -163,11 +154,16 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
 		return ERR_PTR(-ESRCH);
 
 	mm = priv->mm;
-	if (!mm || !mmget_not_zero(mm))
+	if (!mm || !mmget_not_zero(mm)) {
+		put_task_struct(priv->task);
+		priv->task = NULL;
 		return NULL;
+	}
 
 	if (down_read_killable(&mm->mmap_sem)) {
 		mmput(mm);
+		put_task_struct(priv->task);
+		priv->task = NULL;
 		return ERR_PTR(-EINTR);
 	}
 
@@ -195,7 +191,6 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
 	if (pos == mm->map_count && priv->tail_vma)
 		return priv->tail_vma;
 
-	vma_stop(priv);
 	return NULL;
 }
 
@@ -206,21 +201,22 @@ static void *m_next(struct seq_file *m, void *v, loff_t *pos)
 
 	(*pos)++;
 	next = m_next_vma(priv, v);
-	if (!next)
-		vma_stop(priv);
 	return next;
 }
 
 static void m_stop(struct seq_file *m, void *v)
 {
 	struct proc_maps_private *priv = m->private;
+	struct mm_struct *mm = priv->mm;
 
-	if (!IS_ERR_OR_NULL(v))
-		vma_stop(priv);
-	if (priv->task) {
-		put_task_struct(priv->task);
-		priv->task = NULL;
-	}
+	if (!priv->task)
+		return;
+
+	release_task_mempolicy(priv);
+	up_read(&mm->mmap_sem);
+	mmput(mm);
+	put_task_struct(priv->task);
+	priv->task = NULL;
 }
 
 static int proc_maps_open(struct inode *inode, struct file *file,