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Date:   Tue, 7 Jul 2020 13:54:54 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     Jia He <justin.he@arm.com>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Baoquan He <bhe@redhat.com>,
        Chuhong Yuan <hslester96@gmail.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-nvdimm@lists.01.org,
        Kaly Xin <Kaly.Xin@arm.com>
Subject: Re: [PATCH v2 1/3] arm64/numa: export memory_add_physaddr_to_nid as
 EXPORT_SYMBOL_GPL
Message-ID: <20200707115454.GN5913@dhcp22.suse.cz>
References: <20200707055917.143653-1-justin.he@arm.com>
 <20200707055917.143653-2-justin.he@arm.com>
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On Tue 07-07-20 13:59:15, Jia He wrote:
> This exports memory_add_physaddr_to_nid() for module driver to use.
> 
> memory_add_physaddr_to_nid() is a fallback option to get the nid in case
> NUMA_NO_NID is detected.
> 
> Suggested-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Jia He <justin.he@arm.com>
> ---
>  arch/arm64/mm/numa.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
> index aafcee3e3f7e..7eeb31740248 100644
> --- a/arch/arm64/mm/numa.c
> +++ b/arch/arm64/mm/numa.c
> @@ -464,10 +464,11 @@ void __init arm64_numa_init(void)
>  
>  /*
>   * We hope that we will be hotplugging memory on nodes we already know about,
> - * such that acpi_get_node() succeeds and we never fall back to this...
> + * such that acpi_get_node() succeeds. But when SRAT is not present, the node
> + * id may be probed as NUMA_NO_NODE by acpi, Here provide a fallback option.
>   */
>  int memory_add_physaddr_to_nid(u64 addr)
>  {
> -	pr_warn("Unknown node for memory at 0x%llx, assuming node 0\n", addr);
>  	return 0;
>  }
> +EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);

Does it make sense to export a noop function? Wouldn't make more sense
to simply make it static inline somewhere in a header? I haven't checked
whether there is an easy way to do that sanely bu this just hit my eyes.
-- 
Michal Hocko
SUSE Labs