Re: [PATCH v9 2/4] mm: memory_hotplug: override memmap_on_memory when hugetlb_free_vmemmap=on

[Muchun Song <songmuchun@bytedance.com>]

On Tue, May 03, 2022 at 05:23:37PM -0700, Mike Kravetz wrote:
> On 4/29/22 05:18, Muchun Song wrote:
> > When "hugetlb_free_vmemmap=on" and "memory_hotplug.memmap_on_memory"
> > are both passed to boot cmdline, the variable of "memmap_on_memory"
> > will be set to 1 even if the vmemmap pages will not be allocated from
> > the hotadded memory since the former takes precedence over the latter.
> 
> I had to read that sentence a few times before understanding what it was
> trying to say.  Not insisting, but how about this instead:
>

Sorry for my poor English.
 
> Freeing HugeTLB vmemmap pages is not compatible with allocating memmap on
> hot added memory. If "hugetlb_free_vmemmap=on" and
> memory_hotplug.memmap_on_memory" are both passed on the kernel command line,
> freeing hugetlb pages takes precedence.  However, the global variable
> memmap_on_memory will still be set to 1, even though we will not try to
> allocate memmap on hot added memory.
> 
> Not sure if that is more clear or not.
> 

Clearer than mine.

> Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
>

Thanks.