linux-kernel - Re: [PATCH v1] mm/memory_hotplug: Remove move_pfn

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Message-ID: <20190724154532.GE5584@dhcp22.suse.cz>
Date:   Wed, 24 Jul 2019 17:45:32 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Oscar Salvador <osalvador@...e.de>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH v1] mm/memory_hotplug: Remove move_pfn_range()

On Wed 24-07-19 16:23:24, David Hildenbrand wrote:
> Let's remove this indirection. We need the zone in the caller either
> way, so let's just detect it there. Add some documentation for
> move_pfn_range_to_zone() instead.
> 
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Oscar Salvador <osalvador@...e.de>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Pavel Tatashin <pasha.tatashin@...een.com>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>

Acked-by: Michal Hocko <mhocko@...e.com>

> ---
>  mm/memory_hotplug.c | 23 +++++++----------------
>  1 file changed, 7 insertions(+), 16 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index efa5283be36c..e7c3b219a305 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -715,7 +715,11 @@ static void __meminit resize_pgdat_range(struct pglist_data *pgdat, unsigned lon
>  
>  	pgdat->node_spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - pgdat->node_start_pfn;
>  }
> -
> +/*
> + * Associate the pfn range with the given zone, initializing the memmaps
> + * and resizing the pgdat/zone data to span the added pages. After this
> + * call, all affected pages are PG_reserved.
> + */
>  void __ref move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
>  		unsigned long nr_pages, struct vmem_altmap *altmap)
>  {
> @@ -804,20 +808,6 @@ struct zone * zone_for_pfn_range(int online_type, int nid, unsigned start_pfn,
>  	return default_zone_for_pfn(nid, start_pfn, nr_pages);
>  }
>  
> -/*
> - * Associates the given pfn range with the given node and the zone appropriate
> - * for the given online type.
> - */
> -static struct zone * __meminit move_pfn_range(int online_type, int nid,
> -		unsigned long start_pfn, unsigned long nr_pages)
> -{
> -	struct zone *zone;
> -
> -	zone = zone_for_pfn_range(online_type, nid, start_pfn, nr_pages);
> -	move_pfn_range_to_zone(zone, start_pfn, nr_pages, NULL);
> -	return zone;
> -}
> -
>  int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type)
>  {
>  	unsigned long flags;
> @@ -840,7 +830,8 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
>  	put_device(&mem->dev);
>  
>  	/* associate pfn range with the zone */
> -	zone = move_pfn_range(online_type, nid, pfn, nr_pages);
> +	zone = zone_for_pfn_range(online_type, nid, pfn, nr_pages);
> +	move_pfn_range_to_zone(zone, pfn, nr_pages, NULL);
>  
>  	arg.start_pfn = pfn;
>  	arg.nr_pages = nr_pages;
> -- 
> 2.21.0

-- 
Michal Hocko
SUSE Labs