linux-kernel - Re: [PATCH v1 02/29] mm/balloon_compaction: convert balloon_page_delete() to balloon_page

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Message-ID: <8652503b-f00e-46af-b4c0-bec60ebb15ac@redhat.com>
Date: Tue, 1 Jul 2025 11:59:20 +0200
From: David Hildenbrand <david@...hat.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 linux-doc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
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Subject: Re: [PATCH v1 02/29] mm/balloon_compaction: convert
 balloon_page_delete() to balloon_page_finalize()

[...]

>>>> -{
>>>> -	__ClearPageOffline(page);
>>>> -	__ClearPageMovable(page);
>>>> -	set_page_private(page, 0);
>>>> -	/*
>>>> -	 * No touch page.lru field once @page has been isolated
>>>> -	 * because VM is using the field.
>>>> -	 */
>>>> -	if (!PageIsolated(page))
>>>> -		list_del(&page->lru);
>>>
>>> I don't see this check elsewhere, is it because, as per the 1/xx of this series,
>>> because by the time we do the finalize
>>
>> balloon_page_delete() was used on two paths
>>
>> 1) Removing a page from the balloon for deflation through
>> balloon_page_list_dequeue()
>>
>> 2) Removing an isolated page from the balloon for migration in the
>> per-driver migration handlers. Isolated pages were already removed from the
>> balloon list during ... isolation.
>>
>> With this change, 1) does the list_del(&page->lru) manually and 2) only
>> calls balloon_page_finalize().
>>
>> During 1) the same reasoning as in 1/xx applies: isolated pages cannot be in
>> the balloon list.
> 
> Right yeah this is what I thought, thanks!

I'll add some of that to the patch description!

-- 
Cheers,

David / dhildenb