[PATCH v1 2/4] mm: move vma_mmu_pagesize() from hugetlb to vma.c

David Hildenbrand (Arm)
2026-03-06T10:16:36Z

vma_mmu_pagesize() is also queried on non-hugetlb VMAs and does not
really belong into hugetlb.c.

PPC64 provides a custom overwrite with CONFIG_HUGETLB_PAGE, see
arch/powerpc/mm/book3s64/slice.c, so we cannot easily make this a
static inline function.

So let's move it to vma.c and add some proper kerneldoc.

Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
---
include/linux/hugetlb.h | 7 -------
include/linux/mm.h | 2 ++
mm/hugetlb.c | 11 -----------
mm/vma.c | 21 +++++++++++++++++++++
4 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 44c1848a2c21..aaf3d472e6b5 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -777,8 +777,6 @@ static inline unsigned long huge_page_size(const struct hstate *h)
return (unsigned long)PAGE_SIZE << h->order;
}

-extern unsigned long vma_mmu_pagesize(struct vm_area_struct *vma);
-
static inline unsigned long huge_page_mask(struct hstate *h)
{
return h->mask;
@@ -1175,11 +1173,6 @@ static inline unsigned long huge_page_mask(struct hstate *h)
return PAGE_MASK;
}

-static inline unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
-{
- return PAGE_SIZE;
-}
-
static inline unsigned int huge_page_order(struct hstate *h)
{
return 0;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 227809790f1a..22d338933c84 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1327,6 +1327,8 @@ static inline unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
return PAGE_SIZE;
}

+unsigned long vma_mmu_pagesize(struct vm_area_struct *vma);
+
static inline
struct vm_area_struct *vma_find(struct vma_iterator *vmi, unsigned long max)
{
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 66eadfa9e958..f6ecca9aae01 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1017,17 +1017,6 @@ static pgoff_t vma_hugecache_offset(struct hstate *h,
(vma->vm_pgoff >> huge_page_order(h));
}

-/*
- * Return the page size being used by the MMU to back a VMA. In the majority
- * of cases, the page size used by the kernel matches the MMU size. On
- * architectures where it differs, an architecture-specific 'strong'
- * version of this symbol is required.
- */
-__weak unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
-{
- return vma_kernel_pagesize(vma);
-}
-
/*
* Flags for MAP_PRIVATE reservations. These are stored in the bottom
* bits of the reservation map pointer, which are always clear due to
diff --git a/mm/vma.c b/mm/vma.c
index be64f781a3aa..e95fd5a5fe5c 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -3300,3 +3300,24 @@ int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)

return 0;
}
+
+/**
+ * vma_mmu_pagesize - Default MMU page size granularity for this VMA.
+ * @vma: The user mapping.
+ *
+ * In the common case, the default page size used by the MMU matches the
+ * default page size used by the kernel (see vma_kernel_pagesize()). On
+ * architectures where it differs, an architecture-specific 'strong' version
+ * of this symbol is required.
+ *
+ * The default MMU page size is not affected by Transparent Huge Pages
+ * being in effect, or any usage of larger MMU page sizes (either through
+ * architectural huge-page mappings or other explicit/implicit coalescing of
+ * virtual ranges performed by the MMU).
+ *
+ * Return: The default MMU page size granularity for this VMA.
+ */
+__weak unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
+{
+ return vma_kernel_pagesize(vma);
+}
--
2.43.0