linux-kernel - Re: [PATCH v2 3/4] mm/memory_hotplug: Simplify node_states_check_changes

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Message-ID: <52890425-5d16-bd34-4b88-df174a2be7ff@microsoft.com>
Date:   Fri, 21 Sep 2018 14:25:36 +0000
From:   Pasha Tatashin <Pavel.Tatashin@...rosoft.com>
To:     Oscar Salvador <osalvador@...hadventures.net>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
CC:     "mhocko@...e.com" <mhocko@...e.com>,
        "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
        "david@...hat.com" <david@...hat.com>,
        "Jonathan.Cameron@...wei.com" <Jonathan.Cameron@...wei.com>,
        "yasu.isimatu@...il.com" <yasu.isimatu@...il.com>,
        "malat@...ian.org" <malat@...ian.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Oscar Salvador <osalvador@...e.de>
Subject: Re: [PATCH v2 3/4] mm/memory_hotplug: Simplify
 node_states_check_changes_online



On 9/21/18 9:26 AM, Oscar Salvador wrote:
> From: Oscar Salvador <osalvador@...e.de>
> 
> While looking at node_states_check_changes_online, I stumbled
> upon some confusing things.
> 
> Right after entering the function, we find this:
> 
> if (N_MEMORY == N_NORMAL_MEMORY)
>         zone_last = ZONE_MOVABLE;
> 
> This is wrong.
> N_MEMORY cannot really be equal to N_NORMAL_MEMORY.
> My guess is that this wanted to be something like:
> 
> if (N_NORMAL_MEMORY == N_HIGH_MEMORY)
> 
> to check if we have CONFIG_HIGHMEM.
> 
> Later on, in the CONFIG_HIGHMEM block, we have:
> 
> if (N_MEMORY == N_HIGH_MEMORY)
>         zone_last = ZONE_MOVABLE;
> 
> Again, this is wrong, and will never be evaluated to true.
> 
> Besides removing these wrong if statements, I simplified
> the function a bit.
> 
> Signed-off-by: Oscar Salvador <osalvador@...e.de>
> Suggested-by: Pavel Tatashin <pavel.tatashin@...rosoft.com>

Reviewed-by: Pavel Tatashin <pavel.tatashin@...rosoft.com>