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

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Message-ID: <4a759288-baf9-4fe6-9d16-034edf6615f0@kernel.org>
Date: Mon, 9 Feb 2026 20:39:22 +0100
From: "David Hildenbrand (Arm)" <david@...nel.org>
To: Zi Yan <ziy@...dia.com>
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 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?

-- 
Cheers,

David