[PATCH v6 45/71] fs/proc/task_mmu: Stop using linked list and highest_vm_end

[Liam Howlett <liam.howlett@oracle.com>]

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

Remove references to mm_struct linked list and highest_vm_end for when
they are removed

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---
 fs/proc/internal.h |  2 +-
 fs/proc/task_mmu.c | 73 ++++++++++++++++++++++++++--------------------
 2 files changed, 42 insertions(+), 33 deletions(-)

diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 06a80f78433d..f03000764ce5 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -285,7 +285,7 @@ struct proc_maps_private {
 	struct task_struct *task;
 	struct mm_struct *mm;
 #ifdef CONFIG_MMU
-	struct vm_area_struct *tail_vma;
+	struct vma_iterator iter;
 #endif
 #ifdef CONFIG_NUMA
 	struct mempolicy *task_mempolicy;
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 68e65280938e..f42f8501cb55 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -123,12 +123,26 @@ 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)
@@ -152,31 +166,21 @@ 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);
-	priv->tail_vma = get_gate_vma(mm);
-
-	vma = find_vma(mm, last_addr);
-	if (vma)
-		return vma;
+	if (last_addr == -2UL)
+		return get_gate_vma(mm);
 
-	return priv->tail_vma;
+	return proc_get_vma(priv, ppos);
 }
 
 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, *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;
+	if (*ppos == -2UL) {
+		*ppos = -1UL;
+		return NULL;
+	}
+	return proc_get_vma(m->private, ppos);
 }
 
 static void m_stop(struct seq_file *m, void *v)
@@ -872,16 +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;
+	struct mm_struct *mm = priv->mm;
 	struct vm_area_struct *vma;
-	unsigned long last_vma_end = 0;
+	unsigned long vma_start = 0, 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;
@@ -894,8 +898,13 @@ 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;
 
-	for (vma = priv->mm->mmap; vma;) {
+	vma_start = vma->vm_start;
+	do {
 		smap_gather_stats(vma, &mss, 0);
 		last_vma_end = vma->vm_end;
 
@@ -904,6 +913,7 @@ 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) {
@@ -947,7 +957,7 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
 			 *    contains last_vma_end.
 			 *    Iterate VMA' from last_vma_end.
 			 */
-			vma = find_vma(mm, last_vma_end - 1);
+			vma = mas_find(&mas, ULONG_MAX);
 			/* Case 3 above */
 			if (!vma)
 				break;
@@ -961,11 +971,10 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
 				smap_gather_stats(vma, &mss, last_vma_end);
 		}
 		/* Case 2 above */
-		vma = vma->vm_next;
-	}
+	} while ((vma = mas_find(&mas, ULONG_MAX)) != NULL);
 
-	show_vma_header_prefix(m, priv->mm->mmap->vm_start,
-			       last_vma_end, 0, 0, 0, 0);
+empty_set:
+	show_vma_header_prefix(m, vma_start, last_vma_end, 0, 0, 0, 0);
 	seq_pad(m, ' ');
 	seq_puts(m, "[rollup]\n");
 
@@ -1258,6 +1267,7 @@ 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,
@@ -1277,7 +1287,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 		}
 
 		if (type == CLEAR_REFS_SOFT_DIRTY) {
-			for (vma = mm->mmap; vma; vma = vma->vm_next) {
+			mas_for_each(&mas, vma, ULONG_MAX) {
 				if (!(vma->vm_flags & VM_SOFTDIRTY))
 					continue;
 				vma->vm_flags &= ~VM_SOFTDIRTY;
@@ -1289,8 +1299,7 @@ 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, mm->highest_vm_end, &clear_refs_walk_ops,
-				&cp);
+		walk_page_range(mm, 0, -1, &clear_refs_walk_ops, &cp);
 		if (type == CLEAR_REFS_SOFT_DIRTY) {
 			mmu_notifier_invalidate_range_end(&range);
 			flush_tlb_mm(mm);
-- 
2.34.1