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From:   Dan Williams <dan.j.williams@intel.com>
Date:   Fri, 27 Sep 2019 12:32:54 -0700
Message-ID: <CAPcyv4imXWDSoVet4a0CYtO3JxN__f1hq+LCKTnjjF+4HB+6Kw@mail.gmail.com>
Subject: Re: [PATCH] mm, page_alloc: drop pointless static qualifier in build_zonelists()
To:     Kaitao Cheng <pilgrimtao@gmail.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>,
        Michal Hocko <mhocko@suse.com>,
        Oscar Salvador <osalvador@suse.de>,
        Mel Gorman <mgorman@techsingularity.net>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Alexander Duyck <alexander.h.duyck@linux.intel.com>,
        Pasha Tatashin <pavel.tatashin@microsoft.com>,
        Alexander Potapenko <glider@google.com>,
        Linux MM <linux-mm@kvack.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Muchun Song <smuchun@gmail.com>
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On Fri, Sep 27, 2019 at 9:14 AM Kaitao Cheng <pilgrimtao@gmail.com> wrote:
>
> There is no need to make the 'node_order' variable static
> since new value always be assigned before use it.
>
> Signed-off-by: Kaitao Cheng <pilgrimtao@gmail.com>
> Signed-off-by: Muchun Song <smuchun@gmail.com>
> ---
>  mm/page_alloc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 3334a769eb91..c473c304d09f 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5597,7 +5597,7 @@ static void build_thisnode_zonelists(pg_data_t *pgdat)
>
>  static void build_zonelists(pg_data_t *pgdat)
>  {
> -       static int node_order[MAX_NUMNODES];
> +       int node_order[MAX_NUMNODES];

This isn't pointless. This prevents 4KB stack allocation which might overflow.