linux-kernel - Re: [PATCH v9 3/8] mm,memory_hotplug: Factor out adjusting present pages into adjust_present_page

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Date:   Wed, 21 Apr 2021 10:35:26 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     Michal Hocko <mhocko@...e.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 3/8] mm,memory_hotplug: Factor out adjusting present
 pages into adjust_present_page_count()

On Wed, Apr 21, 2021 at 10:31:30AM +0200, Michal Hocko wrote:
> > Given that {offline,online}_pages() is serialized by the memory_hotplug lock,
> > I would say that {node,zone}->{spanned,present}_pages is, at any time, stable?
> > So, no need for the lock even without considering this patch?
> 
> Yes. The resize lock is really only relevant to the parallel struct page
> initialization during early boot. The hotplug usage seems just a left
> over from the past or maybe it has never been really relevant in that
> context.

Ok, I will prepare a follow-up patch to remove the lock in such situations
when this work goes in.


-- 
Oscar Salvador
SUSE L3