linux-kernel - Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel panic

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Date:   Wed, 27 Sep 2017 02:14:05 -0500 (CDT)
From:   Christopher Lameter <cl@...ux.com>
To:     Yang Shi <yang.s@...baba-inc.com>
cc:     penberg@...nel.org, rientjes@...gle.com, iamjoonsoo.kim@....com,
        akpm@...ux-foundation.org, mhocko@...nel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel
 panic

On Wed, 27 Sep 2017, Yang Shi wrote:

> Print out unreclaimable slab info (used size and total size) which
> actual memory usage is not zero (num_objs * size != 0) when:
>   - unreclaimable slabs : all user memory > unreclaim_slabs_oom_ratio
>   - panic_on_oom is set or no killable process

Ok. I like this much more than the earlier releases.

> diff --git a/mm/slab.h b/mm/slab.h
> index 0733628..b0496d1 100644
> --- a/mm/slab.h
> +++ b/mm/slab.h
> @@ -505,6 +505,14 @@ static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
>  void memcg_slab_stop(struct seq_file *m, void *p);
>  int memcg_slab_show(struct seq_file *m, void *p);
>
> +#ifdef CONFIG_SLABINFO
> +void dump_unreclaimable_slab(void);
> +#else
> +static inline void dump_unreclaimable_slab(void)
> +{
> +}
> +#endif

CONFIG_SLABINFO? How does this relate to the oom info? /proc/slabinfo
support is optional. Oom info could be included even if CONFIG_SLABINFO
goes away. Remove the #ifdef?