[PATCH v3 06/15] userfaultfd: move vma_can_userfault out of line

Mike Rapoport
2026-03-30T10:12:07Z

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.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
include/linux/userfaultfd_k.h | 35 ++---------------------------------
mm/userfaultfd.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+), 33 deletions(-)

diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index fd5f42765497..a49cf750e803 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -208,39 +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;
-
- /*
- * If user requested uffd-wp but not enabled pte markers for
- * uffd-wp, then shmem & hugetlbfs are not supported but only
- * anonymous.
- */
- if (!uffd_supports_wp_marker() && (vm_flags & VM_UFFD_WP) &&
- !vma_is_anonymous(vma))
- return false;
-
- /* 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 82e1a3255e1e..d51e080e9216 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -2018,6 +2018,39 @@ 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;
+
+ /*
+ * If user requested uffd-wp but not enabled pte markers for
+ * uffd-wp, then shmem & hugetlbfs are not supported but only
+ * anonymous.
+ */
+ if (!uffd_supports_wp_marker() && (vm_flags & VM_UFFD_WP) &&
+ !vma_is_anonymous(vma))
+ return false;
+
+ /* 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)
{
--
2.53.0