From: David Hildenbrand <david@redhat.com>
To: Mike Rapoport <rppt@linux.ibm.com>,
Dan Williams <dan.j.williams@intel.com>
Cc: Kaly Xin <Kaly.Xin@arm.com>, Dave Jiang <dave.jiang@intel.com>,
Baoquan He <bhe@redhat.com>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Chuhong Yuan <hslester96@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@kernel.org>, Linux MM <linux-mm@kvack.org>,
Vishal Verma <vishal.l.verma@intel.com>,
Jia He <justin.he@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Will Deacon <will@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 1/3] arm64/numa: export memory_add_physaddr_to_nid as EXPORT_SYMBOL_GPL
Date: Wed, 8 Jul 2020 09:21:25 +0200 [thread overview]
Message-ID: <9a009cf6-6c30-91ca-a1a5-9aa090c66631@redhat.com> (raw)
In-Reply-To: <20200708052626.GB386073@linux.ibm.com>
On 08.07.20 07:27, Mike Rapoport wrote:
> On Tue, Jul 07, 2020 at 03:05:48PM -0700, Dan Williams wrote:
>> On Tue, Jul 7, 2020 at 11:01 AM Mike Rapoport <rppt@linux.ibm.com> wrote:
>>>
>>> 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 ;-)
>>
>> So I'd be happy to jump on the train of people wanting to export the
>> ARM stub for this (and add a new ARM stub for phys_to_target_node()),
>> but Will did have a plausibly better idea that I have been meaning to
>> circle back to:
>>
>> http://lore.kernel.org/r/20200325111039.GA32109@willie-the-truck
>>
>> ...i.e. iterate over node data to do the lookup. This would seem to
>> work generically for multiple archs unless I am missing something?
IIRC, only memory assigned to/onlined to a ZONE is represented in the
pgdat node span. E.g., not offline memory blocks.
Esp., when hotplugging + onlining consecutive memory, there won't really
be any intersections in most cases if I am not wrong. It would not be
"intersection" but rather "closest fit".
With overlapping nodes it's even more unclear. Which one to pick?
>
> I think it would work on arm64, power and, most propbably on s390
With only a single dummy node I guess it should work (searching when
there is only a single node does not make too much sense).
> (David?), but not on x86. x86 does not have reserved memory in pgdat,
> it's never memblock_add()'ed (see e820__memblock_setup()).
Can you enlighten me why that is relevant for the memory hotplug path?
(or is it just a general comment to make the function as accurate as
possible for all addresses?)
--
Thanks,
David / dhildenb
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next prev parent reply other threads:[~2020-07-08 7:25 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-07 5:59 [PATCH v2 0/3] Fix and enable pmem as RAM device on arm64 Jia He
2020-07-07 5:59 ` [PATCH v2 1/3] arm64/numa: export memory_add_physaddr_to_nid as EXPORT_SYMBOL_GPL Jia He
2020-07-07 11:35 ` David Hildenbrand
2020-07-07 11:54 ` Michal Hocko
2020-07-07 12:13 ` Mike Rapoport
2020-07-07 12:26 ` David Hildenbrand
2020-07-07 18:00 ` Mike Rapoport
2020-07-07 22:05 ` Dan Williams
2020-07-08 5:27 ` Mike Rapoport
2020-07-08 7:21 ` David Hildenbrand [this message]
2020-07-08 7:38 ` Mike Rapoport
2020-07-08 7:40 ` David Hildenbrand
2020-07-08 7:50 ` Dan Williams
2020-07-08 8:26 ` David Hildenbrand
2020-07-08 8:39 ` Mike Rapoport
2020-07-08 8:45 ` David Hildenbrand
2020-07-08 9:15 ` Mike Rapoport
2020-07-08 9:25 ` David Hildenbrand
2020-07-08 9:45 ` Mike Rapoport
2020-07-08 10:04 ` David Hildenbrand
2020-07-08 15:50 ` Dan Williams
2020-07-08 16:10 ` David Hildenbrand
2020-07-08 16:47 ` Mike Rapoport
2020-07-08 2:20 ` Justin He
2020-07-08 3:56 ` Dan Williams
2020-07-08 4:08 ` Justin He
2020-07-08 4:27 ` Dan Williams
2020-07-08 6:22 ` Mike Rapoport
2020-07-08 6:53 ` Dan Williams
2020-07-08 6:59 ` David Hildenbrand
2020-07-08 7:04 ` Dan Williams
2020-07-08 7:16 ` David Hildenbrand
2020-07-08 7:43 ` Mike Rapoport
2020-07-08 5:32 ` Mike Rapoport
2020-07-08 5:48 ` Dan Williams
2020-07-08 6:19 ` Mike Rapoport
2020-07-08 6:44 ` Dan Williams
2020-07-08 6:56 ` Justin He
2020-07-08 7:00 ` David Hildenbrand
2020-07-07 5:59 ` [RFC PATCH v2 2/3] device-dax: use fallback nid when numa_node is invalid Jia He
2020-07-07 6:08 ` Justin He
2020-07-07 11:34 ` David Hildenbrand
2020-07-08 1:41 ` Justin He
2020-07-07 5:59 ` [PATCH v2 3/3] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done Jia He
2020-07-07 10:06 ` Michal Hocko
2020-07-07 11:31 ` David Hildenbrand
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