Re: [PATCH 1/2] memcg, oom: unmark under_oom after the oom killer is done

[Roman Gushchin <roman.gushchin@linux.dev>]

On Fri, Sep 22, 2023 at 07:05:28AM +0000, Haifeng Xu wrote:
> When application in userland receives oom notification from kernel
> and reads the oom_control file, it's confusing that under_oom is 0
> though the omm killer hasn't finished. The reason is that under_oom
> is cleared before invoking mem_cgroup_out_of_memory(), so move the
> action that unmark under_oom after completing oom handling. Therefore,
> the value of under_oom won't mislead users.
> 
> Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>

Makes sense to me.

Acked-by: Roman Gushchin <roman.gushchin@linux.dev>

Thanks!

> ---
>  mm/memcontrol.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index e8ca4bdcb03c..0b6ed63504ca 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1970,8 +1970,8 @@ static bool mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
>  	if (locked)
>  		mem_cgroup_oom_notify(memcg);
>  
> -	mem_cgroup_unmark_under_oom(memcg);
>  	ret = mem_cgroup_out_of_memory(memcg, mask, order);
> +	mem_cgroup_unmark_under_oom(memcg);
>  
>  	if (locked)
>  		mem_cgroup_oom_unlock(memcg);
> -- 
> 2.25.1
>