From: David Hildenbrand <david@redhat.com>
To: Justin He <Justin.He@arm.com>,
Catalin Marinas <Catalin.Marinas@arm.com>,
Will Deacon <will@kernel.org>
Cc: Baoquan He <bhe@redhat.com>, Kaly Xin <Kaly.Xin@arm.com>,
Chuhong Yuan <hslester96@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Mike Rapoport <rppt@linux.ibm.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/3] arm64/numa: set numa_off to false when numa node is fake
Date: Mon, 6 Jul 2020 15:56:57 +0200 [thread overview]
Message-ID: <ef441868-9336-5cf4-5e5e-78dc3e3e8a96@redhat.com> (raw)
In-Reply-To: <AM6PR08MB4069A96C32135C2C4A8A9FD2F7690@AM6PR08MB4069.eurprd08.prod.outlook.com>
On 06.07.20 14:36, Justin He wrote:
> Hi David, thanks for the comments. See my answer please:
>
>> -----Original Message-----
>> From: David Hildenbrand <david@redhat.com>
>> Sent: Monday, July 6, 2020 4:03 PM
>> To: Justin He <Justin.He@arm.com>; Catalin Marinas
>> <Catalin.Marinas@arm.com>; Will Deacon <will@kernel.org>
>> Cc: 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; Kaly Xin <Kaly.Xin@arm.com>
>> Subject: Re: [PATCH 1/3] arm64/numa: set numa_off to false when numa node
>> is fake
>>
>> On 06.07.20 03:19, Jia He wrote:
>>> Previously, numa_off is set to true unconditionally in dummy_numa_init(),
>>> even if there is a fake numa node.
>>>
>>> But acpi will translate node id to NUMA_NO_NODE(-1) in
>> acpi_map_pxm_to_node()
>>> because it regards numa_off as turning off the numa node.
>>>
>>> Without this patch, pmem can't be probed as a RAM device on arm64 if
>> SRAT table
>>> isn't present.
>>>
>>> $ndctl create-namespace -fe namespace0.0 --mode=devdax --map=dev -s 1g -
>> a 64K
>>> kmem dax0.0: rejecting DAX region [mem 0x240400000-0x2bfffffff] with
>> invalid node: -1
>>> kmem: probe of dax0.0 failed with error -22
>>>
>>> This fixes it by setting numa_off to false.
>>>
>>> Signed-off-by: Jia He <justin.he@arm.com>
>>> ---
>>> arch/arm64/mm/numa.c | 3 ++-
>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
>>> index aafcee3e3f7e..7689986020d9 100644
>>> --- a/arch/arm64/mm/numa.c
>>> +++ b/arch/arm64/mm/numa.c
>>> @@ -440,7 +440,8 @@ static int __init dummy_numa_init(void)
>>> return ret;
>>> }
>>>
>>> - numa_off = true;
>>> + /* force numa_off to be false since we have a fake numa node here
>> */
>>> + numa_off = false;
>>> return 0;
>>> }
>>>
>>>
>>
>> What would happen if we use something like this in drivers/dax/kmem.c
>> instead:
>>
>> numa_node = dev_dax->target_node;
>> if (numa_node == NUMA_NO_NODE)
>> numa_node = memory_add_physaddr_to_nid(kmem_start);
>>
>> and eventually dropping the pr_warn in
>> arm64/memory_add_physaddr_to_nid() ? Would that work?
>
> Yes, it works. I sent a similar patch [1] before. But seems pmem
> maintainer didn't satisfy it. Do you think memory_add_physaddr_to_nid()
> is better than numa_mem_id()?
Well, it's the somewhat-common way to get a NID for memory hotadd.
E.g.,
- drivers/acpi/acpi_memhotplug.c
- drivers/base/memory.c
- drivers/hv/hv_balloon.c
- drivers/virtio/virtio_mem.c
- drivers/xen/balloon.c
use it in combination with add_memory_*()
Especially, ACPI and virtio-mem use it in case NUMA_NO_NID is detected.
--
Thanks,
David / dhildenb
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next prev parent reply other threads:[~2020-07-06 13:58 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-06 1:19 [PATCH 0/3] Fix and enable pmem as RAM on arm64 Jia He
2020-07-06 1:19 ` [PATCH 1/3] arm64/numa: set numa_off to false when numa node is fake Jia He
2020-07-06 8:02 ` David Hildenbrand
2020-07-06 12:36 ` Justin He
2020-07-06 13:56 ` David Hildenbrand [this message]
2020-07-06 10:29 ` Jonathan Cameron
2020-07-06 10:46 ` Jonathan Cameron
2020-07-06 12:47 ` Justin He
2020-07-06 13:03 ` Jonathan Cameron
2020-07-06 1:19 ` [PATCH 2/3] mm/memory_hotplug: harden try_offline_node against bogus nid Jia He
2020-07-06 7:57 ` David Hildenbrand
2020-07-06 13:45 ` Justin He
2020-07-06 1:19 ` [PATCH 3/3] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done Jia He
2020-07-06 7:49 ` David Hildenbrand
2020-07-07 22:10 ` Dan Williams
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