Re: [PATCH v3 1/2] mm, proc: Fix region lost in /proc/self/smaps

[Oleg Nesterov]

On 09/23, Robert Ho wrote:
>
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -147,7 +147,7 @@ m_next_vma(struct proc_maps_private *priv, struct 
> vm_area_struct *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_start : -1UL;
> +             m->version = m_next_vma(m->private, vma) ? vma->vm_end : -1UL;
>  }

OK.

>  static void *m_start(struct seq_file *m, loff_t *ppos)
> @@ -176,14 +176,14 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
>  
>       if (last_addr) {
>               vma = find_vma(mm, last_addr);
> -             if (vma && (vma = m_next_vma(priv, vma)))
> +             if (vma)
>                       return vma;
>       }

I think we can simplify this patch. And imo make it better. How about

        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;
        }

?

This way we do not need other changes in show_map_vma(), and the same vma
won't be reported twice (as 2 different vma's) if it grows in between.

Oleg.