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Date:   Mon, 6 Dec 2021 15:08:10 +0100
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Subject: Re: [RFC PATCH 2/2] mm/vmscan.c: Prevent allocating shrinker_info on
 offlined nodes
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To:     Michal Hocko <mhocko@suse.com>
Cc:     Nico Pache <npache@redhat.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, akpm@linux-foundation.org, shakeelb@google.com,
        ktkhai@virtuozzo.com, shy828301@gmail.com, guro@fb.com,
        vbabka@suse.cz, vdavydov.dev@gmail.com, raquini@redhat.com
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From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
In-Reply-To: <Ya4Y07Iu2ygj5zwZ@dhcp22.suse.cz>
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>> But there might be more missing. Onlining a new zone will get more
>> expensive in setups with a lot of possible nodes (x86-64 shouldn't
>> really be an issue in that regard).
> 
> Honestly, I am not really concerned by platforms with too many nodes
> without any memory. If they want to shoot their feet then that's their
> choice. We can optimize for those if they ever prove to be standar.
>  
>> If we want stable backports, we'll want something simple upfront.
> 
> For stable backports I would be fine by doing your NODE_DATA check in
> the allocator. In upstream I think we should be aiming for a more robust
> solution that is also easier to maintain further down the line. Even if
> that is an investment at this momemnt because the initialization code is
> a mess.
> 

Agreed. I would be curious *why* we decided to dynamically allocate the
pgdat. is this just a historical coincidence or was there real reason to
not allocate it for all possible nodes during boot?

-- 
Thanks,

David / dhildenb