Revert "fs/proc/task_mmu: stop using linked list and highest_vm_end"

This reverts commit bf18fab.

fs/proc/internal.h

@@ -285,7 +285,7 @@ struct proc_maps_private {
 	struct task_struct *task;
 	struct mm_struct *mm;
 #ifdef CONFIG_MMU
-	struct vma_iterator iter;
+	struct vm_area_struct *tail_vma;
 #endif
 #ifdef CONFIG_NUMA
 	struct mempolicy *task_mempolicy;

fs/proc/task_mmu.c

@@ -123,26 +123,12 @@ static void release_task_mempolicy(struct proc_maps_private *priv)
 }
 #endif
 
-static struct vm_area_struct *proc_get_vma(struct proc_maps_private *priv,
-						loff_t *ppos)
-{
-	struct vm_area_struct *vma = vma_next(&priv->iter);
-
-	if (vma) {
-		*ppos = vma->vm_start;
-	} else {
-		*ppos = -2UL;
-		vma = get_gate_vma(priv->mm);
-	}
-
-	return vma;
-}
-
 static void *m_start(struct seq_file *m, loff_t *ppos)
 {
 	struct proc_maps_private *priv = m->private;
 	unsigned long last_addr = *ppos;
 	struct mm_struct *mm;
+	struct vm_area_struct *vma;
 
 	/* See m_next(). Zero at the start or after lseek. */
 	if (last_addr == -1UL)
@@ -166,21 +152,31 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
 		return ERR_PTR(-EINTR);
 	}
 
-	vma_iter_init(&priv->iter, mm, last_addr);
 	hold_task_mempolicy(priv);
-	if (last_addr == -2UL)
-		return get_gate_vma(mm);
+	priv->tail_vma = get_gate_vma(mm);
+
+	vma = find_vma(mm, last_addr);
+	if (vma)
+		return vma;
 
-	return proc_get_vma(priv, ppos);
+	return priv->tail_vma;
 }
 
 static void *m_next(struct seq_file *m, void *v, loff_t *ppos)
 {
-	if (*ppos == -2UL) {
-		*ppos = -1UL;
-		return NULL;
-	}
-	return proc_get_vma(m->private, ppos);
+	struct proc_maps_private *priv = m->private;
+	struct vm_area_struct *next, *vma = v;
+
+	if (vma == priv->tail_vma)
+		next = NULL;
+	else if (vma->vm_next)
+		next = vma->vm_next;
+	else
+		next = priv->tail_vma;
+
+	*ppos = next ? next->vm_start : -1UL;
+
+	return next;
 }
 
 static void m_stop(struct seq_file *m, void *v)
@@ -880,16 +876,16 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
 {
 	struct proc_maps_private *priv = m->private;
 	struct mem_size_stats mss;
-	struct mm_struct *mm = priv->mm;
+	struct mm_struct *mm;
 	struct vm_area_struct *vma;
-	unsigned long vma_start = 0, last_vma_end = 0;
+	unsigned long last_vma_end = 0;
 	int ret = 0;
-	MA_STATE(mas, &mm->mm_mt, 0, 0);
 
 	priv->task = get_proc_task(priv->inode);
 	if (!priv->task)
 		return -ESRCH;
 
+	mm = priv->mm;
 	if (!mm || !mmget_not_zero(mm)) {
 		ret = -ESRCH;
 		goto out_put_task;
@@ -902,13 +898,8 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
 		goto out_put_mm;
 
 	hold_task_mempolicy(priv);
-	vma = mas_find(&mas, 0);
-
-	if (unlikely(!vma))
-		goto empty_set;
 
-	vma_start = vma->vm_start;
-	do {
+	for (vma = priv->mm->mmap; vma;) {
 		smap_gather_stats(vma, &mss, 0);
 		last_vma_end = vma->vm_end;
 
@@ -917,7 +908,6 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
 		 * access it for write request.
 		 */
 		if (mmap_lock_is_contended(mm)) {
-			mas_pause(&mas);
 			mmap_read_unlock(mm);
 			ret = mmap_read_lock_killable(mm);
 			if (ret) {
@@ -961,7 +951,7 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
 			 *    contains last_vma_end.
 			 *    Iterate VMA' from last_vma_end.
 			 */
-			vma = mas_find(&mas, ULONG_MAX);
+			vma = find_vma(mm, last_vma_end - 1);
 			/* Case 3 above */
 			if (!vma)
 				break;
@@ -975,10 +965,11 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
 				smap_gather_stats(vma, &mss, last_vma_end);
 		}
 		/* Case 2 above */
-	} while ((vma = mas_find(&mas, ULONG_MAX)) != NULL);
+		vma = vma->vm_next;
+	}
 
-empty_set:
-	show_vma_header_prefix(m, vma_start, last_vma_end, 0, 0, 0, 0);
+	show_vma_header_prefix(m, priv->mm->mmap->vm_start,
+			       last_vma_end, 0, 0, 0, 0);
 	seq_pad(m, ' ');
 	seq_puts(m, "[rollup]\n");
 
@@ -1271,7 +1262,6 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 		return -ESRCH;
 	mm = get_task_mm(task);
 	if (mm) {
-		MA_STATE(mas, &mm->mm_mt, 0, 0);
 		struct mmu_notifier_range range;
 		struct clear_refs_private cp = {
 			.type = type,
@@ -1291,7 +1281,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 		}
 
 		if (type == CLEAR_REFS_SOFT_DIRTY) {
-			mas_for_each(&mas, vma, ULONG_MAX) {
+			for (vma = mm->mmap; vma; vma = vma->vm_next) {
 				if (!(vma->vm_flags & VM_SOFTDIRTY))
 					continue;
 				vma->vm_flags &= ~VM_SOFTDIRTY;
@@ -1303,7 +1293,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 						0, NULL, mm, 0, -1UL);
 			mmu_notifier_invalidate_range_start(&range);
 		}
-		walk_page_range(mm, 0, -1, &clear_refs_walk_ops, &cp);
+		walk_page_range(mm, 0, mm->highest_vm_end, &clear_refs_walk_ops,
+				&cp);
 		if (type == CLEAR_REFS_SOFT_DIRTY) {
 			mmu_notifier_invalidate_range_end(&range);
 			flush_tlb_mm(mm);