Re: [RFC][2/3] Account and control virtual address space allocations

[Pavel Emelyanov <xemul@openvz.org>]

[snip]

> +int mem_cgroup_update_as(struct mm_struct *mm, long nr_pages)
> +{
> +	int ret = 0;
> +	struct mem_cgroup *mem;
> +	if (mem_cgroup_subsys.disabled)
> +		return ret;
> +
> +	rcu_read_lock();
> +	mem = rcu_dereference(mm->mem_cgroup);
> +	css_get(&mem->css);
> +	rcu_read_unlock();
> +
> +	if (nr_pages > 0) {
> +		if (res_counter_charge(&mem->as_res, (nr_pages * PAGE_SIZE)))
> +			ret = 1;
> +	} else
> +		res_counter_uncharge(&mem->as_res, (-nr_pages * PAGE_SIZE));

No, please, no. Let's make two calls - mem_cgroup_charge_as and mem_cgroup_uncharge_as.

[snip]

> @@ -1117,6 +1117,9 @@ munmap_back:
>  		}
>  	}
>  
> +	if (mem_cgroup_update_as(mm, len >> PAGE_SHIFT))
> +		return -ENOMEM;
> +

Why not use existintg cap_vm_enough_memory and co?

[snip]