Re: [PATCH 05/17] arch, mm: pull out allocation of NODE_DATA to generic code

David Hildenbrand
2024-07-19T16:07:39Z

On 19.07.24 17:51, Jonathan Cameron wrote:
> On Fri, 19 Jul 2024 17:07:35 +0200
> David Hildenbrand <david@redhat.com> wrote:
>
>>>>> - * Allocate node data. Try node-local memory and then any node.
>>>>> - * Never allocate in DMA zone.
>>>>> - */
>>>>> - nd_pa = memblock_phys_alloc_try_nid(nd_size, SMP_CACHE_BYTES, nid);
>>>>> - if (!nd_pa) {
>>>>> - pr_err("Cannot find %zu bytes in any node (initial node: %d)\n",
>>>>> - nd_size, nid);
>>>>> - return;
>>>>> - }
>>>>> - nd = __va(nd_pa);
>>>>> -
>>>>> - /* report and initialize */
>>>>> - printk(KERN_INFO "NODE_DATA(%d) allocated [mem %#010Lx-%#010Lx]\n", nid,
>>>>> - nd_pa, nd_pa + nd_size - 1);
>>>>> - tnid = early_pfn_to_nid(nd_pa >> PAGE_SHIFT);
>>>>> - if (tnid != nid)
>>>>> - printk(KERN_INFO " NODE_DATA(%d) on node %d\n", nid, tnid);
>>>>> -
>>>>> - node_data[nid] = nd;
>>>>> - memset(NODE_DATA(nid), 0, sizeof(pg_data_t));
>>>>> -
>>>>> - node_set_online(nid);
>>>>> -}
>>>>> -
>>>>> /**
>>>>> * numa_cleanup_meminfo - Cleanup a numa_meminfo
>>>>> * @mi: numa_meminfo to clean up
>>>>> @@ -571,6 +538,7 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
>>>>> continue;
>>>>> alloc_node_data(nid);
>>>>> + node_set_online(nid);
>>>>> }
>>>>
>>>> I can spot that we only remove a single node_set_online() call from x86.
>>>>
>>>> What about all the other architectures? Will there be any change in behavior
>>>> for them? Or do we simply set the nodes online later once more?
>>>
>>> On x86 node_set_online() was a part of alloc_node_data() and I moved it
>>> outside so it's called right after alloc_node_data(). On other
>>> architectures the allocation didn't include that call, so there should be
>>> no difference there.
>>
>> But won't their arch code try setting the nodes online at a later stage?
>>
>> And I think, some architectures only set nodes online conditionally
>> (see most other node_set_online() calls).
>>
>> Sorry if I'm confused here, but with now unconditional node_set_online(), won't
>> we change the behavior of other architectures?
> This is moving x86 code to x86 code, not a generic location
> so how would that affect anyone else? Their onlining should be same as
> before.

Yes, see my reply to Mike.

>
> The node onlining difference are a pain (I recall that fun from adding
> generic initiators) as different ordering on x86 and arm64 at least.

That's part of the reason I was confused, because I remember some nasty
inconsistency.

--
Cheers,

David / dhildenb