From: David Hildenbrand <david@redhat.com>
To: Oscar Salvador <osalvador@techadventures.net>
Cc: Jerome Glisse <jglisse@redhat.com>,
akpm@linux-foundation.org, mhocko@suse.com,
dan.j.williams@intel.com, yasu.isimatu@gmail.com,
logang@deltatee.com, dave.jiang@intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Oscar Salvador <osalvador@suse.de>
Subject: Re: [RFC PATCH 2/3] mm/memory_hotplug: Create __shrink_pages and move it to offline_pages
Date: Wed, 8 Aug 2018 10:08:41 +0200 [thread overview]
Message-ID: <7a64e67d-1df9-04ab-cc49-99a39aa90798@redhat.com> (raw)
In-Reply-To: <20180808075614.GB9568@techadventures.net>
On 08.08.2018 09:56, Oscar Salvador wrote:
> On Wed, Aug 08, 2018 at 09:45:37AM +0200, David Hildenbrand wrote:
>> On 08.08.2018 09:38, Oscar Salvador wrote:
>>> On Tue, Aug 07, 2018 at 06:13:45PM -0400, Jerome Glisse wrote:
>>>>> And since we know for sure that memhotplug-code cannot call it with ZONE_DEVICE,
>>>>> I think this can be done easily.
>>>>
>>>> This might change down road but for now this is correct. They are
>>>> talks to enumerate device memory through standard platform mechanisms
>>>> and thus the kernel might see new types of resources down the road and
>>>> maybe we will want to hotplug them directly from regular hotplug path
>>>> as ZONE_DEVICE (lot of hypothetical at this point ;)).
>>>
>>> Well, I think that if that happens this whole thing will become
>>> much easier, since we will not have several paths for doing the same thing.
>>>
>>> Another thing that I realized is that while we want to move all operation-pages
>>> from remove_memory() path to offline_pages(), this can get tricky.
>>>
>>> Unless I am missing something, the devices from HMM and devm are not being registered
>>> against "memory_subsys" struct, and so, they never get to call memory_subsys_offline()
>>> and so offline_pages().
>>>
>>> Which means that we would have to call __remove_zone() from those paths.
>>> But this alone will not work.
>>
>> I mean, they move it to the zone ("replacing online/offlining code"), so
>> they should take of removing it again.
>
> Yeah, I guess so.
>
> I mean, of course we can make this work by placing __remove_zone in devm_memremap_pages_release
> and hmm_devmem_release functions and make sure to call offline_mem_sections first.
> But sounds a bit "hacky"..
>
> Thanks
>
Then it is maybe time to cleary distinguish both types of memory, as
they are fundamentally different when it comes to online/offline behavior.
Ordinary ram:
add_memory ...
online_pages ...
offline_pages
remove_memory
Device memory
add_device_memory ...
remove_device_memory
So adding/removing from the zone and stuff can be handled there.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2018-08-08 8:08 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-07 13:37 [RFC PATCH 0/3] Do not touch pages in remove_memory path osalvador
2018-08-07 13:37 ` [RFC PATCH 1/3] mm/memory_hotplug: Add nid parameter to arch_remove_memory osalvador
2018-08-07 13:37 ` [RFC PATCH 2/3] mm/memory_hotplug: Create __shrink_pages and move it to offline_pages osalvador
2018-08-07 13:52 ` Jerome Glisse
2018-08-07 14:54 ` David Hildenbrand
2018-08-07 15:19 ` Jerome Glisse
2018-08-07 15:28 ` David Hildenbrand
2018-08-07 20:48 ` Oscar Salvador
2018-08-07 22:13 ` Jerome Glisse
2018-08-08 7:38 ` Oscar Salvador
2018-08-08 7:45 ` David Hildenbrand
2018-08-08 7:56 ` Oscar Salvador
2018-08-08 8:08 ` David Hildenbrand [this message]
2018-08-08 13:42 ` Oscar Salvador
2018-08-08 17:55 ` Jerome Glisse
2018-08-08 21:29 ` Oscar Salvador
2018-08-09 7:50 ` Oscar Salvador
2018-08-09 7:52 ` Oscar Salvador
2018-08-08 7:51 ` David Hildenbrand
2018-08-08 8:00 ` Oscar Salvador
2018-08-07 14:59 ` Michal Hocko
2018-08-07 15:18 ` Jerome Glisse
2018-08-08 6:47 ` Michal Hocko
2018-08-08 16:58 ` Jerome Glisse
2018-08-08 21:28 ` Oscar Salvador
2018-08-09 8:24 ` Michal Hocko
2018-08-09 14:27 ` Jerome Glisse
2018-08-09 15:09 ` Michal Hocko
2018-08-09 16:58 ` Jerome Glisse
2018-08-09 20:50 ` Oscar Salvador
2018-08-16 14:58 ` Oscar Salvador
2018-08-16 17:32 ` Jerome Glisse
2018-08-08 9:45 ` Oscar Salvador
2018-08-08 17:33 ` Jerome Glisse
2018-08-07 13:37 ` [RFC PATCH 3/3] mm/memory_hotplug: Refactor shrink_zone/pgdat_span osalvador
2018-08-07 14:16 ` [RFC PATCH 0/3] Do not touch pages in remove_memory path David Hildenbrand
2018-08-07 14:19 ` Oscar Salvador
2018-08-07 14:20 ` David Hildenbrand
2018-08-07 14:28 ` Oscar Salvador
2018-08-07 14:41 ` David Hildenbrand
2018-08-07 14:52 ` Oscar Salvador
2018-08-15 14:05 ` Pavel Tatashin
2018-08-15 14:32 ` Oscar Salvador
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