Re: [PATCH 4.19.y 1/2] mm: hide incomplete nr_indirectly_reclaimable in /proc/zoneinfo

[Vlastimil Babka <vbabka@suse.cz>]

On 4/9/19 7:05 PM, Konstantin Khlebnikov wrote:
> From: Roman Gushchin <guro@fb.com>
> 
> [ commit c29f9010a35604047f96a7e9d6cbabfa36d996d1 from 4.14.y ]
> 
> Yongqin reported that /proc/zoneinfo format is broken in 4.14
> due to commit 7aaf77272358 ("mm: don't show nr_indirectly_reclaimable
> in /proc/vmstat")
> 
> Node 0, zone      DMA
>   per-node stats
>       nr_inactive_anon 403
>       nr_active_anon 89123
>       nr_inactive_file 128887
>       nr_active_file 47377
>       nr_unevictable 2053
>       nr_slab_reclaimable 7510
>       nr_slab_unreclaimable 10775
>       nr_isolated_anon 0
>       nr_isolated_file 0
>       <...>
>       nr_vmscan_write 0
>       nr_vmscan_immediate_reclaim 0
>       nr_dirtied   6022
>       nr_written   5985
>                    74240
>       ^^^^^^^^^^
>   pages free     131656
> 
> The problem is caused by the nr_indirectly_reclaimable counter,
> which is hidden from the /proc/vmstat, but not from the
> /proc/zoneinfo. Let's fix this inconsistency and hide the
> counter from /proc/zoneinfo exactly as from /proc/vmstat.
> 
> BTW, in 4.19+ the counter has been renamed and exported by

This was actually 4.20+ and this mistake is why we initially forgot
about 4.19 stable in [1]

[1]
https://lore.kernel.org/linux-mm/20181030174649.16778-1-guro@fb.com/

> the commit b29940c1abd7 ("mm: rename and change semantics of
> nr_indirectly_reclaimable_bytes"), so there is no such a problem
> anymore.
> 
> Cc: <stable@vger.kernel.org> # 4.19.y
> Fixes: 7aaf77272358 ("mm: don't show nr_indirectly_reclaimable in /proc/vmstat")
> Reported-by: Yongqin Liu <yongqin.liu@linaro.org>
> Signed-off-by: Roman Gushchin <guro@fb.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

Thanks.

> ---
>  mm/vmstat.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 72ef3936d15d..7b8937cb2876 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1550,6 +1550,10 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
>  	if (is_zone_first_populated(pgdat, zone)) {
>  		seq_printf(m, "\n  per-node stats");
>  		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
> +			/* Skip hidden vmstat items. */
> +			if (*vmstat_text[i + NR_VM_ZONE_STAT_ITEMS +
> +					 NR_VM_NUMA_STAT_ITEMS] == '\0')
> +				continue;
>  			seq_printf(m, "\n      %-12s %lu",
>  				vmstat_text[i + NR_VM_ZONE_STAT_ITEMS +
>  				NR_VM_NUMA_STAT_ITEMS],
>