[PATCH v2 10/13] mm: make vm_area_desc utilise vma_flags_t only

Lorenzo Stoakes
2026-01-22T16:09:10Z

Now we have eliminated all uses of vm_area_desc->vm_flags, eliminate this
field, and have mmap_prepare users utilise the vma_flags_t
vm_area_desc->vma_flags field only.

As part of this change we alter is_shared_maywrite() to accept a
vma_flags_t parameter, and introduce is_shared_maywrite_vm_flags() for use
with legacy vm_flags_t flags.

We also update struct mmap_state to add a union between vma_flags and
vm_flags temporarily until the mmap logic is also converted to using
vma_flags_t.

Also update the VMA userland tests to reflect this change.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
include/linux/mm.h | 9 +++++++--
include/linux/mm_types.h | 5 +----
mm/filemap.c | 2 +-
mm/util.c | 2 +-
mm/vma.c | 11 +++++++----
mm/vma.h | 3 +--
tools/testing/vma/vma_internal.h | 9 +++++++--
7 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index e31f72a021ef..37e215de3343 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1290,15 +1290,20 @@ static inline bool vma_is_accessible(const struct vm_area_struct *vma)
return vma->vm_flags & VM_ACCESS_FLAGS;
}

-static inline bool is_shared_maywrite(vm_flags_t vm_flags)
+static inline bool is_shared_maywrite_vm_flags(vm_flags_t vm_flags)
{
return (vm_flags & (VM_SHARED | VM_MAYWRITE)) ==
(VM_SHARED | VM_MAYWRITE);
}

+static inline bool is_shared_maywrite(const vma_flags_t *flags)
+{
+ return vma_flags_test_all(flags, VMA_SHARED_BIT, VMA_MAYWRITE_BIT);
+}
+
static inline bool vma_is_shared_maywrite(const struct vm_area_struct *vma)
{
- return is_shared_maywrite(vma->vm_flags);
+ return is_shared_maywrite(&vma->flags);
}

static inline
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index cdac328b46dc..6d98ff6bc2e5 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -887,10 +887,7 @@ struct vm_area_desc {
/* Mutable fields. Populated with initial state. */
pgoff_t pgoff;
struct file *vm_file;
- union {
- vm_flags_t vm_flags;
- vma_flags_t vma_flags;
- };
+ vma_flags_t vma_flags;
pgprot_t page_prot;

/* Write-only fields. */
diff --git a/mm/filemap.c b/mm/filemap.c
index ebd75684cb0a..6cd7974d4ada 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -4012,7 +4012,7 @@ int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)

int generic_file_readonly_mmap_prepare(struct vm_area_desc *desc)
{
- if (is_shared_maywrite(desc->vm_flags))
+ if (is_shared_maywrite(&desc->vma_flags))
return -EINVAL;
return generic_file_mmap_prepare(desc);
}
diff --git a/mm/util.c b/mm/util.c
index 97cae40c0209..b05ab6f97e11 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -1154,7 +1154,7 @@ int __compat_vma_mmap(const struct file_operations *f_op,

.pgoff = vma->vm_pgoff,
.vm_file = vma->vm_file,
- .vm_flags = vma->vm_flags,
+ .vma_flags = vma->flags,
.page_prot = vma->vm_page_prot,

.action.type = MMAP_NOTHING, /* Default */
diff --git a/mm/vma.c b/mm/vma.c
index 39dcd9ddd4ba..be64f781a3aa 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -15,7 +15,10 @@ struct mmap_state {
unsigned long end;
pgoff_t pgoff;
unsigned long pglen;
- vm_flags_t vm_flags;
+ union {
+ vm_flags_t vm_flags;
+ vma_flags_t vma_flags;
+ };
struct file *file;
pgprot_t page_prot;

@@ -2369,7 +2372,7 @@ static void set_desc_from_map(struct vm_area_desc *desc,

desc->pgoff = map->pgoff;
desc->vm_file = map->file;
- desc->vm_flags = map->vm_flags;
+ desc->vma_flags = map->vma_flags;
desc->page_prot = map->page_prot;
}

@@ -2650,7 +2653,7 @@ static int call_mmap_prepare(struct mmap_state *map,
map->file_doesnt_need_get = true;
map->file = desc->vm_file;
}
- map->vm_flags = desc->vm_flags;
+ map->vma_flags = desc->vma_flags;
map->page_prot = desc->page_prot;
/* User-defined fields. */
map->vm_ops = desc->vm_ops;
@@ -2823,7 +2826,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
return -EINVAL;

/* Map writable and ensure this isn't a sealed memfd. */
- if (file && is_shared_maywrite(vm_flags)) {
+ if (file && is_shared_maywrite_vm_flags(vm_flags)) {
int error = mapping_map_writable(file->f_mapping);

if (error)
diff --git a/mm/vma.h b/mm/vma.h
index bb7fa5d2bde2..062672df8a65 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -286,8 +286,7 @@ static inline void set_vma_from_desc(struct vm_area_struct *vma,
vma->vm_pgoff = desc->pgoff;
if (desc->vm_file != vma->vm_file)
vma_set_file(vma, desc->vm_file);
- if (desc->vm_flags != vma->vm_flags)
- vm_flags_set(vma, desc->vm_flags);
+ vma->flags = desc->vma_flags;
vma->vm_page_prot = desc->page_prot;

/* User-defined fields. */
diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_internal.h
index 2b01794cbd61..2743f12ecf32 100644
--- a/tools/testing/vma/vma_internal.h
+++ b/tools/testing/vma/vma_internal.h
@@ -1009,15 +1009,20 @@ static inline void vma_desc_clear_flags_mask(struct vm_area_desc *desc,
#define vma_desc_clear_flags(desc, ...) \
vma_desc_clear_flags_mask(desc, mk_vma_flags(__VA_ARGS__))

-static inline bool is_shared_maywrite(vm_flags_t vm_flags)
+static inline bool is_shared_maywrite_vm_flags(vm_flags_t vm_flags)
{
return (vm_flags & (VM_SHARED | VM_MAYWRITE)) ==
(VM_SHARED | VM_MAYWRITE);
}

+static inline bool is_shared_maywrite(const vma_flags_t *flags)
+{
+ return vma_flags_test_all(flags, VMA_SHARED_BIT, VMA_MAYWRITE_BIT);
+}
+
static inline bool vma_is_shared_maywrite(struct vm_area_struct *vma)
{
- return is_shared_maywrite(vma->vm_flags);
+ return is_shared_maywrite(&vma->flags);
}

static inline struct vm_area_struct *vma_next(struct vma_iterator *vmi)
--
2.52.0