Re: [PATCH] mm: hugetlb: simplify per-node sysfs creation and removal

[Muchun Song <muchun.song@linux.dev>]

> On Aug 19, 2022, at 14:32, Greg KH <gregkh@linuxfoundation.org> wrote:
> 
> On Fri, Aug 19, 2022 at 01:21:37PM +0800, Muchun Song wrote:
>> The following commit offload per-node sysfs creation and removal to a kworker and
>> did not say why it is needed.  And it also said "I don't know that this is
>> absolutely required".  It seems like the author was not sure as well.  Since it
>> only complicates the code, this patch will revert the changes to simplify the code.
>> 
>>  39da08cb074c ("hugetlb: offload per node attribute registrations")
> 
> Any specific reason why you did not cc: the original author of this
> commit, or anyone else on the patch?

OK. Cc Lee Schermerhorn.

> 
>> We could use memory hotplug notifier to do per-node sysfs creation and removal
>> instead of inserting those operations to node registration and unregistration.
>> Then, it can reduce the code coupling between node.c and hugetlb.c.  Also, it can
>> simplify the code.
> 
> I do not think we had memory hotplug notifier back in 2009 when this
> commit was first written.

Maybe not. Commit 39da08cb074c is merger in 2009. However, hotplug notifier mechanism
is merged in 2006. The document is updated in 2007 (see commit 10020ca246c5).

> 
> How did you test this?  Did you use a HUGETLBFS system and verify that
> everything still works properly?  You are deleting a lot of code (always
> nice), but making sure everything is still operating the same is a good
> thing.

I really did the test (through a VM), it works properly.

Thanks.

> 
> thanks,
> 
> greg k-h