Re: [PATCH 03/15] mm/hugetlb: preserve reservations when shrinking on HIGHMEM

[Muchun Song]

> On Oct 29, 2026, at 04:13, David Hildenbrand (Arm) <david@xxxxxxxxxx> wrote:
> 
> try_to_free_low() drops the hugetlb_lock while freeing lowmem folios.
> set_max_huge_pages() then resumes freeing folios using the
> min_count computed before that unlock. Reservations created in between
> can consequently lose their backing.
> 
> Collect lowmem folios on the caller's existing page_list instead. Keep
> the hugetlb_lock held through both selection passes, and free the combined
> list at the caller's existing unlock point.
> 
> Likely not stable-worthy.
> 
> Fixes: 1121828a0c21 ("hugetlb: call update_and_free_page without hugetlb_lock")
> Signed-off-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

Acked-by: Muchun Song <muchun.song@xxxxxxxxx>

Thanks.