[PATCH 4/6] mm: reintroduce vma_flags_test() as a singular flag test

Lorenzo Stoakes (Oracle)
2026-03-05T10:50:46Z

Since we've now renamed vma_flags_test() to vma_flags_test_any() to be very
clear as to what we are in fact testing, we now have the opportunity to
bring vma_flags_test() back, but for explicitly testing a single VMA flag.

This is useful, as often flag tests are against a single flag, and
vma_flags_test_any(flags, VMA_READ_BIT) reads oddly and potentially causes
confusion.

We use sparse to enforce that users won't accidentally pass vm_flags_t to
this function without it being flagged so this should make it harder to get
this wrong.

Of course, passing vma_flags_t to the function is impossible, as it is a
struct.

Also update the VMA tests to reflect this change.

Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
---
include/linux/mm.h | 17 +++++++++++++++--
mm/hugetlb.c | 2 +-
mm/shmem.c | 4 ++--
tools/testing/vma/include/dup.h | 8 ++++++++
4 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 66b90de30bf6..5622d04c9ba9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1051,6 +1051,19 @@ static __always_inline vma_flags_t __mk_vma_flags(size_t count,
return flags;
}

+/*
+ * Test whether a specific VMA flag is set, e.g.:
+ *
+ * if (vma_flags_test(flags, VMA_READ_BIT)) { ... }
+ */
+static __always_inline bool vma_flags_test(const vma_flags_t *flags,
+ vma_flag_t bit)
+{
+ const unsigned long *bitmap = flags->__vma_flags;
+
+ return test_bit((__force int)bit, bitmap);
+}
+
/*
* Helper macro which bitwise-or combines the specified input flags into a
* vma_flags_t bitmap value. E.g.:
@@ -1957,8 +1970,8 @@ static inline bool vma_desc_is_cow_mapping(struct vm_area_desc *desc)
{
const vma_flags_t *flags = &desc->vma_flags;

- return vma_flags_test_any(flags, VMA_MAYWRITE_BIT) &&
- !vma_flags_test_any(flags, VMA_SHARED_BIT);
+ return vma_flags_test(flags, VMA_MAYWRITE_BIT) &&
+ !vma_flags_test(flags, VMA_SHARED_BIT);
}

#ifndef CONFIG_MMU
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 8286c5db2c12..bd9f3b2d2cb0 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6591,7 +6591,7 @@ long hugetlb_reserve_pages(struct inode *inode,
* attempt will be made for VM_NORESERVE to allocate a page
* without using reserves
*/
- if (vma_flags_test_any(&vma_flags, VMA_NORESERVE_BIT))
+ if (vma_flags_test(&vma_flags, VMA_NORESERVE_BIT))
return 0;

/*
diff --git a/mm/shmem.c b/mm/shmem.c
index 965a8908200b..5e7dcf5bc5d3 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3086,7 +3086,7 @@ static struct inode *__shmem_get_inode(struct mnt_idmap *idmap,
spin_lock_init(&info->lock);
atomic_set(&info->stop_eviction, 0);
info->seals = F_SEAL_SEAL;
- info->flags = vma_flags_test_any(&flags, VMA_NORESERVE_BIT)
+ info->flags = vma_flags_test(&flags, VMA_NORESERVE_BIT)
? SHMEM_F_NORESERVE : 0;
info->i_crtime = inode_get_mtime(inode);
info->fsflags = (dir == NULL) ? 0 :
@@ -5827,7 +5827,7 @@ static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name,
unsigned int i_flags)
{
const unsigned long shmem_flags =
- vma_flags_test_any(&flags, VMA_NORESERVE_BIT) ? SHMEM_F_NORESERVE : 0;
+ vma_flags_test(&flags, VMA_NORESERVE_BIT) ? SHMEM_F_NORESERVE : 0;
struct inode *inode;
struct file *res;

diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h
index ef6b9d963acc..630478f0d583 100644
--- a/tools/testing/vma/include/dup.h
+++ b/tools/testing/vma/include/dup.h
@@ -844,6 +844,14 @@ static inline vma_flags_t __mk_vma_flags(size_t count, const vma_flag_t *bits);
#define mk_vma_flags(...) __mk_vma_flags(COUNT_ARGS(__VA_ARGS__), \
(const vma_flag_t []){__VA_ARGS__})

+static __always_inline bool vma_flags_test(const vma_flags_t *flags,
+ vma_flag_t bit)
+{
+ const unsigned long *bitmap = flags->__vma_flags;
+
+ return test_bit((__force int)bit, bitmap);
+}
+
static __always_inline bool vma_flags_test_any_mask(const vma_flags_t *flags,
vma_flags_t to_test)
{
--
2.53.0