Re: [PATCH v3 7/7] mm: switch deferred split shrinker to list_lru - [s390] panic in __memcg_list_lru_alloc

[Vasily Gorbik]

On Mon, Mar 30, 2026 at 04:56:56PM -0400, Johannes Weiner wrote:
> On Mon, Mar 30, 2026 at 04:41:16PM -0400, Johannes Weiner wrote:
> > Hello Mikhail,
> > 
> > On Mon, Mar 30, 2026 at 06:37:01PM +0200, Mikhail Zaslonko wrote:
> > > with this series in linux-next (since next-20260324) I see a reproducible panic on s390 in the
> > > dump kernel when running NVMe standalone dump (ngdump).
> > > This only happens in the 'capture kernel', normal boot of the same kernel works fine.
> 
> Can you verify whether the kdump kernel boots with
> cgroup_disable=memory?

Yes, that is the only special thing about that dump kernel.
Sorry for not including the command line. x86 crashes more or less the
same way with cgroup_disable=memory. But while I was doing the repro on
x86, you already found the root cause.

> Can you try the below on top of that -next checkout?
> 
> diff --git a/mm/list_lru.c b/mm/list_lru.c
> index 1ccdd45b1d14..7c7024e33653 100644
> --- a/mm/list_lru.c
> +++ b/mm/list_lru.c
> @@ -637,7 +637,7 @@ int __list_lru_init(struct list_lru *lru, bool memcg_aware, struct shrinker *shr
>  	else
>  		lru->shrinker_id = -1;
>  
> -	if (mem_cgroup_kmem_disabled())
> +	if (mem_cgroup_disabled() || mem_cgroup_kmem_disabled())
>  		memcg_aware = false;
>  #endif

Yes, that fixes it for me on s390 and x86. Thank you!