On Mon 29-10-12 17:48:00, Glauber Costa wrote:

On 10/26/2012 03:37 PM, Michal Hocko wrote:

quoted

The root cgroup cannot be destroyed so we never hit it down the
mem_cgroup_pre_destroy path and mem_cgroup_force_empty_write shouldn't
even try to do anything if called for the root.

This means that mem_cgroup_move_parent doesn't have to bother with the
root cgroup and it can assume it can always move charges upwards.

Signed-off-by: Michal Hocko <redacted>
Reviewed-by: Tejun Heo <tj@kernel.org>

I think it would be safer to have this folded in the last patch, to
avoid a weird intermediate state (specially for force_empty).

force_empty excludes root cgroup explicitly so there is no way to fail
here. I have kept VM_BUG_ON for future reference but it also can go away
completely.

Being a single statement, it doesn't confuse review so much.

However, this is also pretty much just a nitpick, do as you prefer.

Reviewed-by: Glauber Costa <redacted>

-- 
Michal Hocko
SUSE Labs

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