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Date:   Mon, 29 Jun 2020 23:24:29 +0300
From:   Mike Rapoport <rppt@kernel.org>
To:     David Rientjes <rientjes@google.com>
Cc:     Su Hui <sh_def@163.com>, akpm@linux-foundation.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm: remove the redundancy code
Message-ID: <20200629202429.GG1492837@kernel.org>
References: <20200629173047.GA38128@ubuntu>
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On Mon, Jun 29, 2020 at 11:50:15AM -0700, David Rientjes wrote:
> 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.

Right, it is:

$ git grep -wn init_currently_empty_zone mm/memory_hotplug.c
mm/memory_hotplug.c:697:            init_currently_empty_zone(zone, start_pfn, nr_pages);


> > ---
> >  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,
> 

-- 
Sincerely yours,
Mike.