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Subject: Re: [Patch v3] mm/page_alloc.c: use NODE_MASK_NONE define used_mask
To:     Wei Yang <richard.weiyang@gmail.com>, <akpm@linux-foundation.org>
CC:     <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        <jgg@ziepe.ca>, <david@redhat.com>, <bhe@redhat.com>
References: <20200329024217.5199-1-richard.weiyang@gmail.com>
From:   John Hubbard <jhubbard@nvidia.com>
Message-ID: <8d6a1cd3-75cf-78c3-b83b-c5208a209f65@nvidia.com>
Date:   Sat, 28 Mar 2020 21:00:26 -0700
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On 3/28/20 7:42 PM, Wei Yang wrote:
> For all 0 nodemask_t, we have already define macro NODE_MASK_NONE.
> Leverage this to define an all clear nodemask.

It would be a little clearer if you used wording more like this:

Subject: [Patch v3] mm/page_alloc.c: use NODE_MASK_NONE in build_zonelists()

Slightly simplify the code by initializing user_mask with
NODE_MASK_NONE, instead of later calling nodes_clear(). This saves
a line of code.


> 
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> 
> ---
> v3: adjust the commit log a little
> v2: use NODE_MASK_NONE as suggested by David Hildenbrand
> ---
>   mm/page_alloc.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index ef790dfad6aa..dfcf2682ed40 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5587,14 +5587,13 @@ static void build_zonelists(pg_data_t *pgdat)
>   {
>   	static int node_order[MAX_NUMNODES];
>   	int node, load, nr_nodes = 0;
> -	nodemask_t used_mask;
> +	nodemask_t used_mask = NODE_MASK_NONE;
>   	int local_node, prev_node;
>   
>   	/* NUMA-aware ordering of nodes */
>   	local_node = pgdat->node_id;
>   	load = nr_online_nodes;
>   	prev_node = local_node;
> -	nodes_clear(used_mask);
>   
>   	memset(node_order, 0, sizeof(node_order));
>   	while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
> 

Honestly, I don't think it's really worth doing a patch for this, but
there's nothing wrong with the diff, so:

Reviewed-by: John Hubbard <jhubbard@nvidia.com>


thanks,
-- 
John Hubbard
NVIDIA