Re: [PATCH 3/5] mm/migrate: use huge_ptep_get() in remove_migration_pte()

[Muchun Song]

> On Jun 25, 2026, at 19:29, Dev Jain <dev.jain@xxxxxxx> wrote:
> 
> remove_migration_pte() converts migration entries back to present PTEs
> after folio migration completes. For hugetlb folios,
> page_vma_mapped_walk() returns the pte pointer to the hugetlb folio in
> pvmw.pte, but the code reads it with ptep_get().
> 
> On arches which provide their own huge_ptep_get() to dereference a huge
> pte pointer, accessing via ptep_get() would cause pte_pfn(),
> pte_present() etc to misbehave.
> 
> It is not clear whether this has a trivially visible effect to userspace.

We are dealing with migration entries here, so the issue mentioned shouldn't
be a problem with any of the architectures. Semantically speaking, we definitely
should fix this.

> 
> Use huge_ptep_get() to dereference a huge pte pointer.
> 
> Fixes: 290408d4a250 ("hugetlb: hugepage migration core")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Dev Jain <dev.jain@xxxxxxx>

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

Thanks