Re: [PATCH 1/2] mm/memcontrol.c: remove meaningless while loop in mem_cgroup_iter()

[Jianyu Zhan]

On Tue, Apr 22, 2014 at 5:47 PM, Michal Hocko <mhocko@xxxxxxx> wrote:
> What about
>   3. last_visited == last_node in the tree
>
> __mem_cgroup_iter_next returns NULL and the iterator would return
> without visiting anything.

Hi,  Michal,

yep,  if 3 last_visited == last_node, then this means we have done a round-trip,
thus __mem_cgroup_iter_next returns NULL, in turn mem_cgroup_iter() return NULL.

This is what comments above mem_cgroup_iter() says:

>Returns references to children of the hierarchy below @root, or
>* @root itself, or %NULL after a full round-trip.

Actually, this condition could be reduced to conditon 2.1

Thanks,
Jianyu Zhan
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