linux-kernel - Re: [PATCH 3/3] mm/page_alloc: Split context in free_area_init

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Message-ID: <CAGM2reY8ODmr=u4bsCrdEX3f-c6NkSuKuEcXowRy=SkuMppjiw@mail.gmail.com>
Date:   Wed, 18 Jul 2018 10:34:19 -0400
From:   Pavel Tatashin <pasha.tatashin@...cle.com>
To:     osalvador@...hadventures.net
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>, iamjoonsoo.kim@....com,
        aaron.lu@...el.com, LKML <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        osalvador@...e.de
Subject: Re: [PATCH 3/3] mm/page_alloc: Split context in free_area_init_node

On Wed, Jul 18, 2018 at 8:47 AM <osalvador@...hadventures.net> wrote:
>
> From: Oscar Salvador <osalvador@...e.de>
>
> If free_area_init_node gets called from memhotplug code,
> we do not need to call calculate_node_totalpages(),
> as the node has no pages.

I am not positive this is safe. Some pgdat fields in
calculate_node_totalpages() are set. Even if those fields are always
set to zeros, pgdat may be reused (i.e. node went offline and later
came back online), so we might still need to set those fields to
zeroes.

Pavel