Re: [PATCH] mm: correctly charge compressed memory to its memcg

[Johannes Weiner <hannes@cmpxchg.org>]

On Thu, Aug 11, 2022 at 04:19:13PM +0800, liliguang wrote:
> From: Li Liguang <liliguang@baidu.com>
> 
> Kswapd will reclaim memory when memory pressure is high, the
> annonymous memory will be compressed and stored in the zpool
> if zswap is enabled. The memcg_kmem_bypass() in
> get_obj_cgroup_from_page() will bypass the kernel thread and
> cause the compressed memory not charged to its memory cgroup.
> 
> Remove the memcg_kmem_bypass() and properly charge compressed
> memory to its corresponding memory cgroup.
> 
> Signed-off-by: Li Liguang <liliguang@baidu.com>

Great catch. I think this qualifies for stable.

Cc: stable@vger.kernel.org # 5.19
Fixes: f4840ccfca25 ("zswap: memcg accounting")
Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Andrew, can you please take this through the MM tree?

> ---
>  mm/memcontrol.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index b69979c9ced5..6a95ea7c5ee7 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2971,7 +2971,7 @@ struct obj_cgroup *get_obj_cgroup_from_page(struct page *page)
>  {
>  	struct obj_cgroup *objcg;
>  
> -	if (!memcg_kmem_enabled() || memcg_kmem_bypass())
> +	if (!memcg_kmem_enabled())
>  		return NULL;
>  
>  	if (PageMemcgKmem(page)) {
> -- 
> 2.32.0 (Apple Git-132)
>