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From: David Hildenbrand <david@redhat.com>
To: Oscar Salvador <osalvador@suse.de>
Cc: mhocko@kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, vbabka@suse.cz, pasha.tatashin@soleen.com
Subject: Re: [RFC PATCH 3/3] mm,memory_hotplug: Allocate memmap from the added memory range
Date: Fri, 20 Nov 2020 10:31:05 +0100	[thread overview]
Message-ID: <ddcb1d70-2e4b-a185-b749-d4f300feec18@redhat.com> (raw)
In-Reply-To: <20201119104847.GA5281@localhost.localdomain>


>>> -	move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_ISOLATE);
>>> +	move_pfn_range_to_zone(zone, pfn, nr_pages, nr_vmemmap_pages, NULL,
>>> +			       MIGRATE_ISOLATE);
>>
>> As mentioned, I'd suggest properly initializing the memmap here
>>
>> if (nr_vmemmap_pages) {
>> 	move_pfn_range_to_zone(zone, pfn, nr_vmemmap_pages, NULL,
>> 			       MIGRATE_UNMOVABLE);
>> }
>> move_pfn_range_to_zone(zone, valid_start_pfn, valid_nr_pages, NULL,
> 
> Sure, agreed.
> 
>>> +	if (!support_memmap_on_memory(size))
>>> +		mhp_flags &= ~MEMHP_MEMMAP_ON_MEMORY;
>>
>> Callers (e.g., virtio-mem) might rely on this. We should reject this with
>> -EINVAL and provide a way for callers to test whether this flag is possible.
> 
> Uhm, we might want to make "support_memmap_on_memory" public, and
> callers who might want to it use can check its return value?
> Or do you have something else in mind?

Right, a way for callers to check if it's supported. 
"mhp_supports_memmap_on_memory" or sth. like that.

Thanks!

-- 
Thanks,

David / dhildenb


  reply	other threads:[~2020-11-20  9:31 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-22 12:58 [RFC PATCH 0/3] Allocate memmap from hotadded memory (per device) Oscar Salvador
2020-10-22 12:58 ` [RFC PATCH 1/3] mm,memory_hotplug: Introduce MHP_MEMMAP_ON_MEMORY Oscar Salvador
2020-10-22 13:04   ` David Hildenbrand
2020-10-22 12:58 ` [RFC PATCH 2/3] mm: Introduce a new Vmemmap page-type Oscar Salvador
2020-11-20 11:20   ` David Hildenbrand
2020-10-22 12:58 ` [RFC PATCH 3/3] mm,memory_hotplug: Allocate memmap from the added memory range Oscar Salvador
2020-11-17 15:38   ` David Hildenbrand
2020-11-19 10:48     ` Oscar Salvador
2020-11-20  9:31       ` David Hildenbrand [this message]
2020-10-22 13:01 ` [RFC PATCH 0/3] Allocate memmap from hotadded memory (per device) David Hildenbrand
2020-10-27 15:40   ` Oscar Salvador
2020-10-27 15:44     ` David Hildenbrand
2020-10-27 15:58       ` Oscar Salvador
2020-10-28 18:47         ` Mike Kravetz
2020-10-29  7:49           ` David Hildenbrand

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