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

[Li, Tianyou]

On 1/22/2026 7:32 PM, Mike Rapoport wrote:
> Hi,
>
> On Tue, Jan 20, 2026 at 10:33:45PM +0800, Tianyou Li wrote:
> > Encapsulate the mhp_init_memmap_on_memory() and online_pages() into
> > online_memory_block_pages(). Thus we can further optimize the
> > set_zone_contiguous() to check the whole memory block range, instead
> > of check the zone contiguous in separate range.
> >
> > Correspondingly, encapsulate the mhp_deinit_memmap_on_memory() and
> > offline_pages() into offline_memory_block_pages().
> >
> > Tested-by: Yuan Liu <yuan1.liu@xxxxxxxxx>
> > Reviewed-by: Yuan Liu <yuan1.liu@xxxxxxxxx>
> > Signed-off-by: Tianyou Li <tianyou.li@xxxxxxxxx>
> > ---
> >   drivers/base/memory.c          | 53 ++++++---------------------
> >   include/linux/memory_hotplug.h | 18 +++++-----
> >   mm/memory_hotplug.c            | 65 +++++++++++++++++++++++++++++++---
> >   3 files changed, 80 insertions(+), 56 deletions(-)
> >
> > 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?


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.


> >   	mem_hotplug_done();
> > +
> >   	return ret;
> >   }
> >