Re: [PATCH v1 05/29] mm/balloon_compaction: make PageOffline sticky until the page is freed

David Hildenbrand
2025-07-01T08:12:13Z

On 30.06.25 18:14, Zi Yan wrote:
> On 30 Jun 2025, at 12:01, Lorenzo Stoakes wrote:
>
>> On Mon, Jun 30, 2025 at 02:59:46PM +0200, David Hildenbrand wrote:
>>> Let the page freeing code handle clearing the page type.
>>
>> Why is this advantageous? We want to keep the page marked offline for longer?
>>
>>>
>>> Acked-by: Zi Yan <ziy@nvidia.com>
>>> Acked-by: Harry Yoo <harry.yoo@oracle.com>
>>> Signed-off-by: David Hildenbrand <david@redhat.com>
>>
>> On assumption this UINT_MAX stuff is sane :)) I mean this is straightforward I
>> guess:
>
> This is how page type is cleared.
> See: https://elixir.bootlin.com/linux/v6.15.4/source/include/linux/page-flags.h#L1013.
>
> I agree with you that patch 4 should have a comment in free_pages_prepare()
> about what the code is for and why UINT_MAX is used.

I can add a comment

/* Reset the page_type -> _mapcount to -1 */

To patch #4.

--
Cheers,

David / dhildenb