On Fri, Aug 28, 2015 at 11:25:30AM -0400, Tejun Heo wrote:
> On the default hierarchy, all memory consumption will be accounted
> together and controlled by the same set of limits. Always enable
> kmemcg on the default hierarchy.
IMO we should introduce a boot time knob for disabling it, because kmem
accounting is still not perfect, besides some users might prefer to go
w/o it for performance reasons.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> ---
> mm/memcontrol.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c94b686..8a5dd01 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4362,6 +4362,13 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
> if (ret)
> return ret;
>
> + /* kmem is always accounted together on the default hierarchy */
> + if (cgroup_on_dfl(css->cgroup)) {
> + ret = memcg_activate_kmem(memcg, PAGE_COUNTER_MAX);
> + if (ret)
> + return ret;
> + }
> +
This is a wrong place for this. The kernel will panic on an attempt to
create a sub memcg, because memcg_init_kmem already enables kmem
accounting in this case. I guess we should add this hunk to
memcg_propagate_kmem instead.
Thanks,
Vladimir
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