On Fri, Jan 29, 2021 at 12:34:51PM +0100, David Hildenbrand wrote:
> Let's count the number of CMA pages per zone and print them in
> /proc/zoneinfo.
>
> Having access to the total number of CMA pages per zone is helpful for
> debugging purposes to know where exactly the CMA pages ended up, and to
> figure out how many pages of a zone might behave differently, even after
> some of these pages might already have been allocated.
>
> As one example, CMA pages part of a kernel zone cannot be used for
> ordinary kernel allocations but instead behave more like ZONE_MOVABLE.
>
> For now, we are only able to get the global nr+free cma pages from
> /proc/meminfo and the free cma pages per zone from /proc/zoneinfo.
>
> Example after this patch when booting a 6 GiB QEMU VM with
> "hugetlb_cma=2G":
> # cat /proc/zoneinfo | grep cma
> cma 0
> nr_free_cma 0
> cma 0
> nr_free_cma 0
> cma 524288
> nr_free_cma 493016
> cma 0
> cma 0
> # cat /proc/meminfo | grep Cma
> CmaTotal: 2097152 kB
> CmaFree: 1972064 kB
>
> Note: We print even without CONFIG_CMA, just like "nr_free_cma"; this way,
> one can be sure when spotting "cma 0", that there are definetly no
> CMA pages located in a zone.
>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
> Cc: Mike Rapoport <rppt@xxxxxxxxxx>
> Cc: Oscar Salvador <osalvador@xxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: linux-api@xxxxxxxxxxxxxxx
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Looks good to me, I guess it is better to print it unconditionally
so the layout does not change.
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
thanks
> ---
>
> The third time is the charm.
>
> v2 -> v3:
> - Print even without CONFIG_CMA. Use zone_cma_pages().
> - Adjust patch description
> - Dropped Oscar's RB due to the changes
>
> v1 -> v2:
> - Print/track only with CONFIG_CMA
> - Extend patch description
>
> ---
> include/linux/mmzone.h | 15 +++++++++++++++
> mm/page_alloc.c | 1 +
> mm/vmstat.c | 6 ++++--
> 3 files changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index ae588b2f87ef..caafd5e37080 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -503,6 +503,9 @@ struct zone {
> * bootmem allocator):
> * managed_pages = present_pages - reserved_pages;
> *
> + * cma pages is present pages that are assigned for CMA use
> + * (MIGRATE_CMA).
> + *
> * So present_pages may be used by memory hotplug or memory power
> * management logic to figure out unmanaged pages by checking
> * (present_pages - managed_pages). And managed_pages should be used
> @@ -527,6 +530,9 @@ struct zone {
> atomic_long_t managed_pages;
> unsigned long spanned_pages;
> unsigned long present_pages;
> +#ifdef CONFIG_CMA
> + unsigned long cma_pages;
> +#endif
>
> const char *name;
>
> @@ -624,6 +630,15 @@ static inline unsigned long zone_managed_pages(struct zone *zone)
> return (unsigned long)atomic_long_read(&zone->managed_pages);
> }
>
> +static inline unsigned long zone_cma_pages(struct zone *zone)
> +{
> +#ifdef CONFIG_CMA
> + return zone->cma_pages;
> +#else
> + return 0;
> +#endif
> +}
> +
> static inline unsigned long zone_end_pfn(const struct zone *zone)
> {
> return zone->zone_start_pfn + zone->spanned_pages;
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index b031a5ae0bd5..9a82375bbcb2 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2168,6 +2168,7 @@ void __init init_cma_reserved_pageblock(struct page *page)
> }
>
> adjust_managed_page_count(page, pageblock_nr_pages);
> + page_zone(page)->cma_pages += pageblock_nr_pages;
> }
> #endif
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 7758486097f9..b2537852d498 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1642,14 +1642,16 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
> "\n high %lu"
> "\n spanned %lu"
> "\n present %lu"
> - "\n managed %lu",
> + "\n managed %lu"
> + "\n cma %lu",
> zone_page_state(zone, NR_FREE_PAGES),
> min_wmark_pages(zone),
> low_wmark_pages(zone),
> high_wmark_pages(zone),
> zone->spanned_pages,
> zone->present_pages,
> - zone_managed_pages(zone));
> + zone_managed_pages(zone),
> + zone_cma_pages(zone));
>
> seq_printf(m,
> "\n protection: (%ld",
> --
> 2.29.2
>
>
--
Oscar Salvador
SUSE L3
