Re: [PATCH v3 3/3] mm/huge_memory: skip device-private PMDs in madvise_free_huge_pmd

[Gregory Price <gourry@gourry.net>]

On Fri, Jul 10, 2026 at 03:55:23AM -0700, Usama Arif wrote:
> 
> Fixes: 368076f52ebe ("mm/huge_memory: add device-private THP support to PMD operations")
> Cc: <stable@vger.kernel.org>
> Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
> Reviewed-by: Zi Yan <ziy@nvidia.com>
> Reviewed-by: Balbir Singh <balbirs@nvidia.com>
> Signed-off-by: Usama Arif <usama.arif@linux.dev>

Reviewed-by: Gregory Price <gourry@gourry.net>

> ---
>  mm/huge_memory.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index c0892cc533a9..7ae21b006b68 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2297,8 +2297,8 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>  		goto out;
>  
>  	if (unlikely(!pmd_present(orig_pmd))) {
> -		VM_BUG_ON(thp_migration_supported() &&
> -				  !pmd_is_migration_entry(orig_pmd));
> +		VM_WARN_ON_ONCE(!pmd_is_migration_entry(orig_pmd) &&
> +				!pmd_is_device_private_entry(orig_pmd));

I just realized, are there softleaf entries we wouldn't want to WARN on?
If not, should all three of these patches just be something like
pmd_is_softleaf()?

x_is_softleaf() does not exist, just curious if it should, and not
worth holding up the patch.

~Gregory