On Fri, Feb 08 2013, Glauber Costa wrote:
> With the infrastructure we now have, we can add an element to a memcg
> LRU list instead of the global list. The memcg lists are still
> per-node.
[...]
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index b9e1941..bfb4b5b 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3319,6 +3319,36 @@ static inline void memcg_resume_kmem_account(void)
> current->memcg_kmem_skip_account--;
> }
>
> +static struct mem_cgroup *mem_cgroup_from_kmem_page(struct page *page)
> +{
> + struct page_cgroup *pc;
> + struct mem_cgroup *memcg = NULL;
> +
> + pc = lookup_page_cgroup(page);
> + if (!PageCgroupUsed(pc))
> + return NULL;
> +
> + lock_page_cgroup(pc);
> + if (PageCgroupUsed(pc))
> + memcg = pc->mem_cgroup;
> + unlock_page_cgroup(pc);
Once we drop the lock, is there anything that needs protection
(e.g. PageCgroupUsed)? If there's no problem, then what's the point of
taking the lock?
> + return memcg;
> +}
> +
[...]
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