linux-kernel - Re: [PATCH V5 - Rebased] mm/hotplug: Reorder memblock_[free|remove]() calls in try_remove

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Message-ID: <6ed925d3-03bf-14cb-3c3c-aeba6bbe20c7@redhat.com>
Date:   Thu, 13 Jun 2019 08:14:08 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Anshuman Khandual <anshuman.khandual@....com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        catalin.marinas@....com, will.deacon@....com,
        ard.biesheuvel@....com, osalvador@...e.de, mhocko@...e.com,
        mark.rutland@....com
Subject: Re: [PATCH V5 - Rebased] mm/hotplug: Reorder memblock_[free|remove]()
 calls in try_remove_memory()

On 13.06.19 03:54, Andrew Morton wrote:
> On Wed, 12 Jun 2019 08:53:33 +0200 David Hildenbrand <david@...hat.com> wrote:
> 
>>>>> ...
>>>>>
>>>>>
>>>>> - Rebased on linux-next (next-20190611)
>>>>
>>>> Yet the patch you've prepared is designed for 5.3.  Was that
>>>> deliberate, or should we be targeting earlier kernels?
>>>
>>> It was deliberate for 5.3 as a preparation for upcoming reworked arm64 hot-remove.
>>>
>>
>> We should probably add to the patch description something like "This is
>> a preparation for arm64 memory hotremove. The described issue is not
>> relevant on other architectures."
> 
> Please.  And is there any reason to merge it separately?  Can it be
> [patch 1/3] in the "arm64/mm: Enable memory hot remove" series?
> 

Nothing that the patch can be considered a cleanup:

"
mm/hotplug: Reorder memblock_[free|remove]() calls in try_remove_memory()

In add_memory_resource() we have:

	memblock_add_node(start, size, nid)
	...
	arch_add_memory(nid, start, size, &restrictions);
	...
	create_memory_block_devices(start, size);

While in try_remove_memory() we have:

	memblock_free(start, size);
	memblock_remove(start, size);
	...
	remove_memory_block_devices(start, size);
	arch_remove_memory(nid, start, size, NULL);

Let's restore the correct order by removing the memblock after
arch_remove_memory().
"

I think with such a description, we can include it now. Andrew?

-- 

Thanks,

David / dhildenb