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Date:   Tue, 7 Jul 2020 21:00:43 +0300
From:   Mike Rapoport <rppt@linux.ibm.com>
To:     David Hildenbrand <david@redhat.com>
Cc:     Michal Hocko <mhocko@kernel.org>, Jia He <justin.he@arm.com>,
        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>,
        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
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On Tue, Jul 07, 2020 at 02:26:08PM +0200, David Hildenbrand wrote:
> On 07.07.20 14:13, Mike Rapoport wrote:
> > On Tue, Jul 07, 2020 at 01:54:54PM +0200, Michal Hocko wrote:
> >> 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.
> > 
> > We'll need to either add a CONFIG_ option or arch specific callback to
> > make both non-empty (x86, powerpc, ia64) and empty (arm64, sh)
> > implementations coexist ...
> 
> Note: I have a similar dummy (return 0) patch for s390x lying around here.

Then we'll call it a tie - 3:3 ;-)
 
> -- 
> Thanks,
> 
> David / dhildenb
> 

-- 
Sincerely yours,
Mike.