Re: [PATCH v1] drivers/base/node.c: Simplify unregister_memory_block_under_nodes()

[David Hildenbrand]

On 19.07.19 11:13, Michal Hocko wrote:
> On Fri 19-07-19 11:05:51, David Hildenbrand wrote:
>> On 19.07.19 10:42, Michal Hocko wrote:
>>> On Thu 18-07-19 16:22:39, David Hildenbrand wrote:
>>>> We don't allow to offline memory block devices that belong to multiple
>>>> numa nodes. Therefore, such devices can never get removed. It is
>>>> sufficient to process a single node when removing the memory block.
>>>>
>>>> Remember for each memory block if it belongs to no, a single, or mixed
>>>> nodes, so we can use that information to skip unregistering or print a
>>>> warning (essentially a safety net to catch BUGs).
>>>
>>> I do not really like NUMA_NO_NODE - 1 thing. This is yet another invalid
>>> node that is magic. Why should we even care? In other words why is this
>>> patch an improvement?
>>
>> Oh, and to answer that part of the question:
>>
>> We no longer have to iterate over each pfn of a memory block to be removed.
> 
> Is it possible that we are overzealous when unregistering syfs files and
> we should simply skip the pfn walk even without this change?
> 

I assume you mean something like v1 without the warning/"NUMA_NO_NODE -1"?

See what I have right now below.