Re: [PATCH 3/3] memcg: bail out proactive reclaim when memcg is dying

[Usama Arif]

On Tue, 23 Jun 2026 14:27:56 +0800 Jiayuan Chen <jiayuan.chen@xxxxxxxxx> wrote:

> From: Jiayuan Chen <jiayuan.chen@xxxxxxxxxx>
> 
> Proactive reclaim via memory.reclaim can run for a long time - swap I/O
> or thrashing again dominating the latency - and delays cgroup removal in
> the same way.
> 
> Mitigate this by stopping the reclaim once memcg_is_dying().
> 
> Reported-by: Zhou Yingfu <yingfu.zhou@xxxxxxxxxx>
> Cc: Jiayuan Chen <jiayuan.chen@xxxxxxxxx>
> Signed-off-by: Jiayuan Chen <jiayuan.chen@xxxxxxxxxx>
> ---
>  mm/vmscan.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 8190c4abec84..1162b7f76655 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -7922,6 +7922,9 @@ int user_proactive_reclaim(char *buf,
>  		if (memcg) {
>  			unsigned int reclaim_options;
>  
> +			if (memcg_is_dying(memcg))
> +				break;
> +

This exits the reclaim loop with nr_reclaimed < nr_to_reclaim, but the
function then returns 0 and memory_reclaim() reports a successful write.
I think you want to return -EAGAIN here?


>  			reclaim_options = MEMCG_RECLAIM_MAY_SWAP |
>  					  MEMCG_RECLAIM_PROACTIVE;
>  			reclaimed = try_to_free_mem_cgroup_pages(memcg,
> -- 
> 2.43.0
> 
>