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Date:   Mon, 29 Jun 2020 11:50:15 -0700 (PDT)
From:   David Rientjes <rientjes@google.com>
To:     Su Hui <sh_def@163.com>
cc:     akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [PATCH] mm: remove the redundancy code
In-Reply-To: <20200629173047.GA38128@ubuntu>
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References: <20200629173047.GA38128@ubuntu>
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On Tue, 30 Jun 2020, Su Hui wrote:

> remove the redundancy code, the zone_start_pfn
> is assigned from zone->zone_start_pfn
> Signed-off-by: Su Hui <sh_def@163.com>

I don't think this is redundant, it's used by memory hotplug when onlining 
new memory.

> ---
>  mm/page_alloc.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 3c4eb750a199..3372a8c9fbc4 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6215,8 +6215,6 @@ void __meminit init_currently_empty_zone(struct zone *zone,
>  	if (zone_idx > pgdat->nr_zones)
>  		pgdat->nr_zones = zone_idx;
>  
> -	zone->zone_start_pfn = zone_start_pfn;
> -
>  	mminit_dprintk(MMINIT_TRACE, "memmap_init",
>  			"Initialising map node %d zone %lu pfns %lu -> %lu\n",
>  			pgdat->node_id,