linux-kernel - Re: [PATCH v3] mm/page_alloc: clear page->private in free_pages

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Message-ID: <72534BCC-2581-4BFA-B3BC-2CC6FF1B1E7A@nvidia.com>
Date: Mon, 09 Feb 2026 14:42:28 -0500
From: Zi Yan <ziy@...dia.com>
To: "David Hildenbrand (Arm)" <david@...nel.org>
Cc: Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>, linux-mm@...ck.org,
 akpm@...ux-foundation.org, vbabka@...e.cz, surenb@...gle.com,
 mhocko@...e.com, jackmanb@...gle.com, hannes@...xchg.org, npiggin@...il.com,
 linux-kernel@...r.kernel.org, kasong@...cent.com, hughd@...gle.com,
 chrisl@...nel.org, ryncsn@...il.com, stable@...r.kernel.org,
 willy@...radead.org
Subject: Re: [PATCH v3] mm/page_alloc: clear page->private in
 free_pages_prepare()

On 9 Feb 2026, at 14:39, David Hildenbrand (Arm) wrote:

> On 2/9/26 18:44, Zi Yan wrote:
>> On 9 Feb 2026, at 12:36, David Hildenbrand (Arm) wrote:
>>
>>> On 2/9/26 17:33, Zi Yan wrote:
>>>>
>>>>
>>>> I agree. Silently fixing non zero ->private just moves the work/responsibility
>>>> from users to core mm. They could do better. :)
>>>>
>>>> We can have a patch or multiple patches to fix users do not zero ->private
>>>> when freeing a page and add the patch below.
>>>
>>> Do we know roughly which ones don't zero it out?
>>
>> So far based on [1], I found:
>>
>> 1. shmem_swapin_folio() in mm/shmem.c does not zero ->swap.val (overlapping
>> with private);
>> 2. __free_slab() in mm/slub.c does not zero ->inuse, ->objects, ->frozen
>> (overlapping with private).
>>
>> Mikhail found ttm_pool_unmap_and_free() in drivers/gpu/drm/ttm/ttm_pool.c
>> does not zero ->private, which stores page order.
>>
>
> Looks doable then :) Should we take v3 as a quick fix to backport then?

Sounds good to me.

Best Regards,
Yan, Zi