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Date: Wed, 28 Nov 2018 14:07:51 -0800
From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] mm, show_mem: drop pgdat_resize_lock in show_mem()
Message-Id: <20181128140751.e79de952a3fdfdac3aab75e9@linux-foundation.org>
In-Reply-To: <20181128210815.2134-1-richard.weiyang@gmail.com>
References: <20181128210815.2134-1-richard.weiyang@gmail.com>
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Sender: owner-linux-mm@kvack.org
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To: Wei Yang <richard.weiyang@gmail.com>
Cc: mhocko@suse.com, jweiner@fb.com, linux-mm@kvack.org

On Thu, 29 Nov 2018 05:08:15 +0800 Wei Yang <richard.weiyang@gmail.com> wrote:

> Function show_mem() is used to print system memory status when user
> requires or fail to allocate memory. Generally, this is a best effort
> information and not willing to affect core mm subsystem.
> 
> The data protected by pgdat_resize_lock is mostly correct except there is:
> 
>    * page struct defer init
>    * memory hotplug

What is the advantage in doing this?  What problem does the taking of
that lock cause?