Re: [PATCH] memcg: Replace mm->owner with mm->memcg

[Oleg Nesterov]

On 05/02, Eric W. Biederman wrote:
>
> +static void mem_cgroup_fork(struct task_struct *tsk)
> +{
> +	struct cgroup_subsys_state *css;
> +
> +	rcu_read_lock();
> +	css = task_css(tsk, memory_cgrp_id);
> +	if (css && css_tryget(css))
> +		task_update_memcg(tsk, mem_cgroup_from_css(css));
> +	rcu_read_unlock();
> +}

Why do we need it?

The child's mm->memcg was already initialized by mm_init_memcg() and we can't
race with migrate until cgroup_threadgroup_change_end() ?

Oleg.