linux-kernel - Re: [PATCH v2] mm: show_mem: show number of zspages in show_free

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Message-ID: <68db0611-3ecd-4cd1-8003-285981e21ca3@suse.cz>
Date: Tue, 2 Sep 2025 15:54:40 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Thadeu Lima de Souza Cascardo <cascardo@...lia.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
 Brendan Jackman <jackmanb@...gle.com>, Johannes Weiner <hannes@...xchg.org>,
 Zi Yan <ziy@...dia.com>, Minchan Kim <minchan@...nel.org>,
 Sergey Senozhatsky <senozhatsky@...omium.org>,
 Yosry Ahmed <yosry.ahmed@...ux.dev>, Nhat Pham <nphamcs@...il.com>,
 Chengming Zhou <chengming.zhou@...ux.dev>, SeongJae Park <sj@...nel.org>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, kernel-dev@...lia.com
Subject: Re: [PATCH v2] mm: show_mem: show number of zspages in
 show_free_areas

On 9/2/25 14:49, Thadeu Lima de Souza Cascardo wrote:
> When OOM is triggered, it will show where the pages might be for each zone.
> When using zram or zswap, it might look like lots of pages are missing.
> After this patch, zspages are shown as below.
> 
> [   48.792859] Node 0 DMA free:2812kB boost:0kB min:60kB low:72kB high:84kB reserved_highatomic:0KB free_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB zspages:11160kB present:15992kB managed:15360kB mlocked:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
> [   48.792962] lowmem_reserve[]: 0 956 956 956 956
> [   48.792988] Node 0 DMA32 free:3512kB boost:0kB min:3912kB low:4888kB high:5864kB reserved_highatomic:0KB free_highatomic:0KB active_anon:0kB inactive_anon:28kB active_file:8kB inactive_file:16kB unevictable:0kB writepending:0kB zspages:916780kB present:1032064kB managed:978944kB mlocked:0kB bounce:0kB free_pcp:500kB local_pcp:248kB free_cma:0kB
> [   48.793118] lowmem_reserve[]: 0 0 0 0 0
> 
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...lia.com>

Acked-by: Vlastimil Babka <vbabka@...e.cz>

> ---
> v2:
> - fix build when CONFIG_ZSMALLOC is not enabled
> ---
>  mm/show_mem.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/mm/show_mem.c b/mm/show_mem.c
> index 41999e94a56d623726ea92f3f38785e8b218afe5..c563d9adfa87765a8736e91c1f68d824b03eaea8 100644
> --- a/mm/show_mem.c
> +++ b/mm/show_mem.c
> @@ -310,6 +310,7 @@ static void show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_z
>  			" inactive_file:%lukB"
>  			" unevictable:%lukB"
>  			" writepending:%lukB"
> +			" zspages:%lukB"
>  			" present:%lukB"
>  			" managed:%lukB"
>  			" mlocked:%lukB"
> @@ -332,6 +333,11 @@ static void show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_z
>  			K(zone_page_state(zone, NR_ZONE_INACTIVE_FILE)),
>  			K(zone_page_state(zone, NR_ZONE_UNEVICTABLE)),
>  			K(zone_page_state(zone, NR_ZONE_WRITE_PENDING)),
> +#if IS_ENABLED(CONFIG_ZSMALLOC)
> +			K(zone_page_state(zone, NR_ZSPAGES)),
> +#else
> +			0UL,
> +#endif
>  			K(zone->present_pages),
>  			K(zone_managed_pages(zone)),
>  			K(zone_page_state(zone, NR_MLOCK)),
> 
> ---
> base-commit: b320789d6883cc00ac78ce83bccbfe7ed58afcf0
> change-id: 20250902-show_mem_zspages-d090ea0bd1d4
> 
> Best regards,