Re: [PATCH v3] mm/page_alloc: clear page->private in free_pages_prepare()

[Baolin Wang <baolin.wang@linux.alibaba.com>]

On 2/10/26 3:42 AM, Zi Yan wrote:
> 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);

After Kairui’s series [1], the shmem part looks good to me. As we no 
longer skip the swapcache now, we shouldn’t clear the ->swap.val of a 
swapcache folio if failed to swap-in.

[1]https://lore.kernel.org/all/20251219195751.61328-1-ryncsn@gmail.com/T/#mcba8a32e1021dc28ce1e824c9d042dca316a30d7

>>> 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.