[patch 097/166] proc: remove m_cache_vma

Andrew Morton
2020-04-07T03:09:13Z

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: proc: remove m_cache_vma

Instead of setting m->version in the show method, set it in m_next(),
where it should be. Also remove the fallback code for failing to find a
vma, or version being zero.

Link: http://lkml.kernel.org/r/20200317193201.9924-2-adobriyan@gmail.com
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>
---

fs/proc/task_mmu.c | 38 ++++++--------------------------------
1 file changed, 6 insertions(+), 32 deletions(-)

--- a/fs/proc/task_mmu.c~proc-remove-m_cache_vma
+++ a/fs/proc/task_mmu.c
@@ -131,21 +131,14 @@ m_next_vma(struct proc_maps_private *pri
return vma->vm_next ?: priv->tail_vma;
}

-static void m_cache_vma(struct seq_file *m, struct vm_area_struct *vma)
-{
- if (m->count < m->size) /* vma is copied successfully */
- m->version = m_next_vma(m->private, vma) ? vma->vm_end : -1UL;
-}
-
static void *m_start(struct seq_file *m, loff_t *ppos)
{
struct proc_maps_private *priv = m->private;
unsigned long last_addr = m->version;
struct mm_struct *mm;
struct vm_area_struct *vma;
- unsigned int pos = *ppos;

- /* See m_cache_vma(). Zero at the start or after lseek. */
+ /* See m_next(). Zero at the start or after lseek. */
if (last_addr == -1UL)
return NULL;

@@ -170,28 +163,11 @@ static void *m_start(struct seq_file *m,
hold_task_mempolicy(priv);
priv->tail_vma = get_gate_vma(mm);

- if (last_addr) {
- vma = find_vma(mm, last_addr - 1);
- if (vma && vma->vm_start <= last_addr)
- vma = m_next_vma(priv, vma);
- if (vma)
- return vma;
- }
-
- m->version = 0;
- if (pos < mm->map_count) {
- for (vma = mm->mmap; pos; pos--) {
- m->version = vma->vm_start;
- vma = vma->vm_next;
- }
+ vma = find_vma(mm, last_addr);
+ if (vma)
return vma;
- }
-
- /* we do not bother to update m->version in this case */
- if (pos == mm->map_count && priv->tail_vma)
- return priv->tail_vma;

- return NULL;
+ return priv->tail_vma;
}

static void *m_next(struct seq_file *m, void *v, loff_t *pos)
@@ -201,6 +177,8 @@ static void *m_next(struct seq_file *m,

(*pos)++;
next = m_next_vma(priv, v);
+ m->version = next ? next->vm_start : -1UL;
+
return next;
}

@@ -359,7 +337,6 @@ done:
static int show_map(struct seq_file *m, void *v)
{
show_map_vma(m, v);
- m_cache_vma(m, v);
return 0;
}

@@ -843,8 +820,6 @@ static int show_smap(struct seq_file *m,
seq_printf(m, "ProtectionKey: %8u\n", vma_pkey(vma));
show_smap_vma_flags(m, vma);

- m_cache_vma(m, vma);
-
return 0;
}

@@ -1883,7 +1858,6 @@ static int show_numa_map(struct seq_file
seq_printf(m, " kernelpagesize_kB=%lu", vma_kernel_pagesize(vma) >> 10);
out:
seq_putc(m, '\n');
- m_cache_vma(m, vma);
return 0;
}

_