proc: use ppos instead of m->version

The ppos is a private cursor, just like m->version.  Use the canonical
cursor, not a special one.
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/20200317193201.9924-3-adobriyan@gmail.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/task_mmu.c

@@ -134,7 +134,7 @@ m_next_vma(struct proc_maps_private *priv, struct vm_area_struct *vma)
 static void *m_start(struct seq_file *m, loff_t *ppos)
 {
 	struct proc_maps_private *priv = m->private;
-	unsigned long last_addr = m->version;
+	unsigned long last_addr = *ppos;
 	struct mm_struct *mm;
 	struct vm_area_struct *vma;
 
@@ -170,14 +170,13 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
 	return priv->tail_vma;
 }
 
-static void *m_next(struct seq_file *m, void *v, loff_t *pos)
+static void *m_next(struct seq_file *m, void *v, loff_t *ppos)
 {
 	struct proc_maps_private *priv = m->private;
 	struct vm_area_struct *next;
 
-	(*pos)++;
 	next = m_next_vma(priv, v);
-	m->version = next ? next->vm_start : -1UL;
+	*ppos = next ? next->vm_start : -1UL;
 
 	return next;
 }