[PATCH v13 43/70] fs/proc/task_mmu: stop using linked list and highest_vm_end

Liam Howlett
2022-08-22T15:10:20Z

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 9f70bc1c2766..8b4f3073f8f5 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)
@@ -876,16 +880,16 @@ 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;
@@ -898,8 +902,13 @@ 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;

@@ -908,6 +917,7 @@ 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) {
@@ -951,7 +961,7 @@ 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;
@@ -965,11 +975,10 @@ 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");

@@ -1262,6 +1271,7 @@ 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,
@@ -1281,7 +1291,7 @@ 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;
@@ -1293,8 +1303,7 @@ 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);
--
2.35.1