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

[Baolin Wang]

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@xxxxxxxxx/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.