Re: [PATCH v2 4/5] proc/task_mmu: read proc/pid/smaps_rollup under per-vma lock

[David Hildenbrand (Arm)]

On 9/9/26 19:58, Suren Baghdasaryan wrote:
> On Wed, Sep 9, 2026 at 10:23 AM David Hildenbrand (Arm)
> <david@xxxxxxxxxx> wrote:
>>
>>
>>> -     vma_start = vma->vm_start;
>>> -     do {
>>> -             smap_gather_stats(priv, vma, &mss, vma->vm_start);
>>> -             last_vma_end = vma->vm_end;
>>> +     if (!IS_ERR(vma) && vma != get_gate_vma(lock_ctx->mm))
>>> +             vma_start = vma->vm_start;
>>> +
>>> +     while (vma) {
>>> +             if (IS_ERR(vma)) {
>>> +                     ret = PTR_ERR(vma);
>>> +                     goto out_unlock;
>>> +             }
>>> +
>>
>> Can we add a comment whey we break (and not e.g., continue) whenw e hit the gate
>> VMA?
>>
>> (I seriously don't kmow ... should I know? :) )
> 
> The way m_next() is implemented, the gate VMA always placed at the end
> of the address space, so the next VMA will be NULL and we can break
> once we see the gate. But now that I'm looking closer into this code,
> reading smaps_rollup file does not invoke m_next(), so we should never
> encounter a gate VMA (it's not in the maple tree, so for_each_vma()
> should never return it). I think I can remove the special handling for
> that case.
> 
> Thanks for the question, David! It made me realize we can simplify this further.

good! :)

-- 
Cheers,

David