Re: [PATCH v2 1/5] userfaultfd: move vma_can_userfault out of line

Liam R. Howlett
2025-11-26T15:06:31Z

* Mike Rapoport <rppt@kernel.org> [251125 13:39]:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
>
> vma_can_userfault() has grown pretty big and it's not called on
> performance critical path.
>
> Move it out of line.
>
> No functional changes.
>
> Reviewed-by: David Hildenbrand (Red Hat) <david@kernel.org>
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>

> ---
> include/linux/userfaultfd_k.h | 36 ++---------------------------------
> mm/userfaultfd.c | 34 +++++++++++++++++++++++++++++++++
> 2 files changed, 36 insertions(+), 34 deletions(-)
>
> diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
> index c0e716aec26a..e4f43e7b063f 100644
> --- a/include/linux/userfaultfd_k.h
> +++ b/include/linux/userfaultfd_k.h
> @@ -208,40 +208,8 @@ static inline bool userfaultfd_armed(struct vm_area_struct *vma)
> return vma->vm_flags & __VM_UFFD_FLAGS;
> }
>
> -static inline bool vma_can_userfault(struct vm_area_struct *vma,
> - vm_flags_t vm_flags,
> - bool wp_async)
> -{
> - vm_flags &= __VM_UFFD_FLAGS;
> -
> - if (vma->vm_flags & VM_DROPPABLE)
> - return false;
> -
> - if ((vm_flags & VM_UFFD_MINOR) &&
> - (!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma)))
> - return false;
> -
> - /*
> - * If wp async enabled, and WP is the only mode enabled, allow any
> - * memory type.
> - */
> - if (wp_async && (vm_flags == VM_UFFD_WP))
> - return true;
> -
> -#ifndef CONFIG_PTE_MARKER_UFFD_WP
> - /*
> - * If user requested uffd-wp but not enabled pte markers for
> - * uffd-wp, then shmem & hugetlbfs are not supported but only
> - * anonymous.
> - */
> - if ((vm_flags & VM_UFFD_WP) && !vma_is_anonymous(vma))
> - return false;
> -#endif
> -
> - /* By default, allow any of anon|shmem|hugetlb */
> - return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||
> - vma_is_shmem(vma);
> -}
> +bool vma_can_userfault(struct vm_area_struct *vma, vm_flags_t vm_flags,
> + bool wp_async);
>
> static inline bool vma_has_uffd_without_event_remap(struct vm_area_struct *vma)
> {
> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> index af61b95c89e4..8dc964389b0d 100644
> --- a/mm/userfaultfd.c
> +++ b/mm/userfaultfd.c
> @@ -1977,6 +1977,40 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
> return moved ? moved : err;
> }
>
> +bool vma_can_userfault(struct vm_area_struct *vma, vm_flags_t vm_flags,
> + bool wp_async)
> +{
> + vm_flags &= __VM_UFFD_FLAGS;
> +
> + if (vma->vm_flags & VM_DROPPABLE)
> + return false;
> +
> + if ((vm_flags & VM_UFFD_MINOR) &&
> + (!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma)))
> + return false;
> +
> + /*
> + * If wp async enabled, and WP is the only mode enabled, allow any
> + * memory type.
> + */
> + if (wp_async && (vm_flags == VM_UFFD_WP))
> + return true;
> +
> +#ifndef CONFIG_PTE_MARKER_UFFD_WP
> + /*
> + * If user requested uffd-wp but not enabled pte markers for
> + * uffd-wp, then shmem & hugetlbfs are not supported but only
> + * anonymous.
> + */
> + if ((vm_flags & VM_UFFD_WP) && !vma_is_anonymous(vma))
> + return false;
> +#endif
> +
> + /* By default, allow any of anon|shmem|hugetlb */
> + return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||
> + vma_is_shmem(vma);
> +}
> +
> static void userfaultfd_set_vm_flags(struct vm_area_struct *vma,
> vm_flags_t vm_flags)
> {
> --
> 2.50.1
>