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Subject: Re: [PACTH v1] mm, proc: Implement /proc/<pid>/totmaps
To: Mateusz Guzik <mguzik@redhat.com>
References: <1470758743-17685-1-git-send-email-robert.foss@collabora.com>
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From: Robert Foss <robert.foss@collabora.com>
Message-ID: <54a4277a-dbc8-0815-6fc8-d3c11d2a930c@collabora.com>
Date: Wed, 10 Aug 2016 11:39:12 -0400
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On 2016-08-09 04:17 PM, Robert Foss wrote:
>>> +static int totmaps_proc_show(struct seq_file *m, void *data)
>>> +{
>>> +    struct proc_maps_private *priv = m->private;
>>> +    struct mm_struct *mm;
>>> +    struct vm_area_struct *vma;
>>> +    struct mem_size_stats *mss_sum = priv->mss;
>>> +
>>> +    /* reference to priv->task already taken */
>>> +    /* but need to get the mm here because */
>>> +    /* task could be in the process of exiting */
>>> +    mm = get_task_mm(priv->task);
>>> +    if (!mm || IS_ERR(mm))
>>> +        return -EINVAL;
>>> +
>>
>> That's not how it's done in smaps.
>
> Alright, I'll have to look into the difference between this approach and
> the smaps one.


I had a look at show_smaps(), and it's not entirely clear to me what the 
advantage of doing it show_smaps() way.

mm = get_task_mm(priv->task) is needed to iterate through all of the 
mappings. Is there a preferable way of doing that?