linux-kernel - Re: [PATCH v8 2/3] mm/memory hotplug/unplug: Add online_memory_block_pages() and offline_memory_block

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Message-ID: <705d63f7-2451-46bc-b1f0-bef718b82283@intel.com>
Date: Sat, 24 Jan 2026 20:30:57 +0800
From: "Li, Tianyou" <tianyou.li@...el.com>
To: Mike Rapoport <rppt@...nel.org>
CC: David Hildenbrand <david@...nel.org>, Oscar Salvador <osalvador@...e.de>,
	Wei Yang <richard.weiyang@...il.com>, Michal Hocko <mhocko@...e.com>,
	<linux-mm@...ck.org>, Yong Hu <yong.hu@...el.com>, Nanhai Zou
	<nanhai.zou@...el.com>, Yuan Liu <yuan1.liu@...el.com>, Tim Chen
	<tim.c.chen@...ux.intel.com>, Qiuxu Zhuo <qiuxu.zhuo@...el.com>, Yu C Chen
	<yu.c.chen@...el.com>, Pan Deng <pan.deng@...el.com>, Chen Zhang
	<zhangchen.kidd@...com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 2/3] mm/memory hotplug/unplug: Add
 online_memory_block_pages() and offline_memory_block_pages()


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@...el.com>
>> Reviewed-by: Yuan Liu <yuan1.liu@...el.com>
>> Signed-off-by: Tianyou Li <tianyou.li@...el.com>
>> ---
>>   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;
>>   }
>>