Re: [PATCH v8 2/3] mm/memory hotplug/unplug: Add online_memory_block_pages() and offline_memory_block_pages()

[Li, Tianyou]

On 1/27/2026 2:58 PM, Mike Rapoport wrote:
> On Sat, Jan 24, 2026 at 08:30:57PM +0800, Li, Tianyou wrote:
> > On 1/22/2026 7:32 PM, Mike Rapoport wrote:
> > > > diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> > > > index 751f248ca4a8..ea4d6fbf34fd 100644
> > > > --- a/drivers/base/memory.c
> > > > +++ b/drivers/base/memory.c
> > > > @@ -246,31 +246,12 @@ static int memory_block_online(struct memory_block *mem)
> > > >    		nr_vmemmap_pages = mem->altmap->free;
> > > >    	mem_hotplug_begin();
> > > > -	if (nr_vmemmap_pages) {
> > > > -		ret = mhp_init_memmap_on_memory(start_pfn, nr_vmemmap_pages, zone);
> > > > -		if (ret)
> > > > -			goto out;
> > > > -	}
> > > > -
> > > > -	ret = online_pages(start_pfn + nr_vmemmap_pages,
> > > > -			   nr_pages - nr_vmemmap_pages, zone, mem->group);
> > > > -	if (ret) {
> > > > -		if (nr_vmemmap_pages)
> > > > -			mhp_deinit_memmap_on_memory(start_pfn, nr_vmemmap_pages);
> > > > -		goto out;
> > > > -	}
> > > > -
> > > > -	/*
> > > > -	 * Account once onlining succeeded. If the zone was unpopulated, it is
> > > > -	 * now already properly populated.
> > > > -	 */
> > > > -	if (nr_vmemmap_pages)
> > > > -		adjust_present_page_count(pfn_to_page(start_pfn), mem->group,
> > > > -					  nr_vmemmap_pages);
> > > > -
> > > > -	mem->zone = zone;
> > > > -out:
> > > > +	ret = online_memory_block_pages(start_pfn, nr_pages, nr_vmemmap_pages,
> > > > +					zone, mem->group);
> > > > +	if (!ret)
> > > > +		mem->zone = zone;
> > > I think we can move most of memory_block_online() to the new function and
> > > pass struct memory_block to it.
> > > I'd suggest
> > > 	
> > > 	int mhp_block_online(struct memory_block *block)
> > >
> > > and
> > >
> > > 	int mhp_block_offline(struct memory_block *block)
> > >
> > > Other than that LGTM.
> >
> > It's doable, if not other comments I can change the code. Would it look like
> > moving the functions to mm/memory_hotplug.c, change the name to
> > mhp_block_online() and mhp_block_offline(), and change the references where
> > the original function invoked in drivers/base/memory.c?
> Yeah, that's what I thought about.
>
> Even more broadly, I think the functionality in drivers/base/memory.c
> belongs to mm/ much more than to drivers/ but that's surely out of scope
> for these patches.
>   


Thanks Mike for the confirmation.


> > My prior thoughts on this was just break the code as small pieces as
> > necessary to handle the pages online part together with zone contiguous
> > state update.
> IMHO moving the entire function is cleaner, let's hear what David and Oscar
> think.


Sure. Actually the patch has been ready with the mhp_block_online() and 
mhp_block_offline() moved to memory_hotplug.c, the 
online_memory_block_pages() and offline_memory_block_pages() remains but 
as static function.


Once get feedback from David and Oscar, I can change them accordingly.