linux-kernel - Re: [PATCH 4/5] mm/memory_hotplug: Simplify node_states_check_changes

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Message-ID: <20180921103029.GA15555@techadventures.net>
Date:   Fri, 21 Sep 2018 12:30:29 +0200
From:   Oscar Salvador <osalvador@...hadventures.net>
To:     Pasha Tatashin <Pavel.Tatashin@...rosoft.com>
Cc:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "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 4/5] mm/memory_hotplug: Simplify
 node_states_check_changes_online

On Fri, Sep 21, 2018 at 12:15:53AM +0000, Pasha Tatashin wrote:

Hi Pavel,

> But what if that changes, will this function need to change as well?

That's true.

> Should not we have:
> 			else
> 				arg->status_change_nid_high = -1; ?
> 
> > +		} else
> > +			arg->status_change_nid_high = -1;

Yes, I forgot about that else.

> I think it is simpler to have something like this:
> 
>         int nid = zone_to_nid(zone);
> 
>         arg->status_change_nid_high = -1;
>         arg->status_change_nid = -1;
>         arg->status_change_nid = -1;
> 
>         if (!node_state(nid, N_MEMORY))
>                 arg->status_change_nid = nid; 
>         if (zone_idx(zone) <= ZONE_NORMAL && !node_state(nid, N_NORMAL_MEMORY))
>                 arg->status_change_nid_normal = nid; 
> #ifdef CONFIG_HIGHMEM
>         if (zone_idx(zone) <= N_HIGH_MEMORY && !node_state(nid, N_HIGH_MEMORY))
>                 arg->status_change_nid_high = nid; 
> #endif

I can write it that way, I also like it more.

I will send it in V2.

Thanks for reviewing it!
-- 
Oscar Salvador
SUSE L3