Re: [PATCH v2 09/13] mm: update all remaining mmap_prepare users to use vma_flags_t

Pedro Falcato
2026-02-06T17:46:45Z

On Thu, Jan 22, 2026 at 04:06:18PM +0000, Lorenzo Stoakes wrote:
> We will be shortly removing the vm_flags_t field from vm_area_desc so we
> need to update all mmap_prepare users to only use the dessc->vma_flags
> field.
>
> This patch achieves that and makes all ancillary changes required to make
> this possible.
>
> This lays the groundwork for future work to eliminate the use of vm_flags_t
> in vm_area_desc altogether and more broadly throughout the kernel.
>
> While we're here, we take the opportunity to replace VM_REMAP_FLAGS with
> VMA_REMAP_FLAGS, the vma_flags_t equivalent.
>
> No functional changes intended.
>
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> ---
> drivers/char/mem.c | 6 +++---
> drivers/dax/device.c | 10 +++++-----
> fs/aio.c | 2 +-
> fs/erofs/data.c | 5 +++--
> fs/ext4/file.c | 4 ++--
> fs/ntfs3/file.c | 2 +-
> fs/orangefs/file.c | 4 ++--
> fs/ramfs/file-nommu.c | 2 +-
> fs/resctrl/pseudo_lock.c | 2 +-
> fs/romfs/mmap-nommu.c | 2 +-
> fs/xfs/xfs_file.c | 4 ++--
> fs/zonefs/file.c | 3 ++-
> include/linux/dax.h | 8 ++++----
> include/linux/mm.h | 24 +++++++++++++++++++-----
> kernel/relay.c | 2 +-
> mm/memory.c | 17 ++++++++---------
> 16 files changed, 56 insertions(+), 41 deletions(-)
>
> diff --git a/drivers/char/mem.c b/drivers/char/mem.c
> index 52039fae1594..cca4529431f8 100644
> --- a/drivers/char/mem.c
> +++ b/drivers/char/mem.c
> @@ -306,7 +306,7 @@ static unsigned zero_mmap_capabilities(struct file *file)
> /* can't do an in-place private mapping if there's no MMU */
> static inline int private_mapping_ok(struct vm_area_desc *desc)
> {
> - return is_nommu_shared_mapping(desc->vm_flags);
> + return is_nommu_shared_vma_flags(&desc->vma_flags);
> }
> #else
>
> @@ -360,7 +360,7 @@ static int mmap_mem_prepare(struct vm_area_desc *desc)
>
> desc->vm_ops = &mmap_mem_ops;
>
> - /* Remap-pfn-range will mark the range VM_IO. */
> + /* Remap-pfn-range will mark the range with the I/O flag. */
> mmap_action_remap_full(desc, desc->pgoff);
> /* We filter remap errors to -EAGAIN. */
> desc->action.error_hook = mmap_filter_error;
> @@ -520,7 +520,7 @@ static int mmap_zero_prepare(struct vm_area_desc *desc)
> #ifndef CONFIG_MMU
> return -ENOSYS;
> #endif
> - if (desc->vm_flags & VM_SHARED)
> + if (vma_desc_test_flags(desc, VMA_SHARED_BIT))
> return shmem_zero_setup_desc(desc);
>
> desc->action.success_hook = mmap_zero_private_success;
> diff --git a/drivers/dax/device.c b/drivers/dax/device.c
> index 22999a402e02..528e81240c4d 100644
> --- a/drivers/dax/device.c
> +++ b/drivers/dax/device.c
> @@ -13,7 +13,7 @@
> #include "dax-private.h"
> #include "bus.h"
>
> -static int __check_vma(struct dev_dax *dev_dax, vm_flags_t vm_flags,
> +static int __check_vma(struct dev_dax *dev_dax, vma_flags_t flags,
> unsigned long start, unsigned long end, struct file *file,
> const char *func)
> {
> @@ -24,7 +24,7 @@ static int __check_vma(struct dev_dax *dev_dax, vm_flags_t vm_flags,
> return -ENXIO;
>
> /* prevent private mappings from being established */
> - if ((vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
> + if (!vma_flags_test(&flags, VMA_MAYSHARE_BIT)) {
> dev_info_ratelimited(dev,
> "%s: %s: fail, attempted private mapping\n",
> current->comm, func);
> @@ -53,7 +53,7 @@ static int __check_vma(struct dev_dax *dev_dax, vm_flags_t vm_flags,
> static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
> const char *func)
> {
> - return __check_vma(dev_dax, vma->vm_flags, vma->vm_start, vma->vm_end,
> + return __check_vma(dev_dax, vma->flags, vma->vm_start, vma->vm_end,
> vma->vm_file, func);
> }
>
> @@ -306,14 +306,14 @@ static int dax_mmap_prepare(struct vm_area_desc *desc)
> * fault time.
> */
> id = dax_read_lock();
> - rc = __check_vma(dev_dax, desc->vm_flags, desc->start, desc->end, filp,
> + rc = __check_vma(dev_dax, desc->vma_flags, desc->start, desc->end, filp,
> __func__);
> dax_read_unlock(id);
> if (rc)
> return rc;
>
> desc->vm_ops = &dax_vm_ops;
> - desc->vm_flags |= VM_HUGEPAGE;
> + vma_desc_set_flags(desc, VMA_HUGEPAGE_BIT);
> return 0;
> }
>
> diff --git a/fs/aio.c b/fs/aio.c
> index 0a23a8c0717f..59b67b8da1b2 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -394,7 +394,7 @@ static const struct vm_operations_struct aio_ring_vm_ops = {
>
> static int aio_ring_mmap_prepare(struct vm_area_desc *desc)
> {
> - desc->vm_flags |= VM_DONTEXPAND;
> + vma_desc_set_flags(desc, VMA_DONTEXPAND_BIT);
> desc->vm_ops = &aio_ring_vm_ops;
> return 0;
> }
> diff --git a/fs/erofs/data.c b/fs/erofs/data.c
> index bb13c4cb8455..e7bc29e764c6 100644
> --- a/fs/erofs/data.c
> +++ b/fs/erofs/data.c
> @@ -438,11 +438,12 @@ static int erofs_file_mmap_prepare(struct vm_area_desc *desc)
> if (!IS_DAX(file_inode(desc->file)))
> return generic_file_readonly_mmap_prepare(desc);
>
> - if ((desc->vm_flags & VM_SHARED) && (desc->vm_flags & VM_MAYWRITE))
> + if (vma_desc_test_flags(desc, VMA_SHARED_BIT) &&
> + vma_desc_test_flags(desc, VMA_MAYWRITE_BIT))
> return -EINVAL;
>
> desc->vm_ops = &erofs_dax_vm_ops;
> - desc->vm_flags |= VM_HUGEPAGE;
> + vma_desc_set_flags(desc, VMA_HUGEPAGE_BIT);
> return 0;
> }
> #else
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 7a8b30932189..dfd5f4fe1647 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -822,13 +822,13 @@ static int ext4_file_mmap_prepare(struct vm_area_desc *desc)
> * We don't support synchronous mappings for non-DAX files and
> * for DAX files if underneath dax_device is not synchronous.
> */
> - if (!daxdev_mapping_supported(desc->vm_flags, file_inode(file), dax_dev))
> + if (!daxdev_mapping_supported(desc, file_inode(file), dax_dev))
> return -EOPNOTSUPP;
>
> file_accessed(file);
> if (IS_DAX(file_inode(file))) {
> desc->vm_ops = &ext4_dax_vm_ops;
> - desc->vm_flags |= VM_HUGEPAGE;
> + vma_desc_set_flags(desc, VMA_HUGEPAGE_BIT);
> } else {
> desc->vm_ops = &ext4_file_vm_ops;
> }
> diff --git a/fs/ntfs3/file.c b/fs/ntfs3/file.c
> index 2e7b2e566ebe..2902fc6d9a85 100644
> --- a/fs/ntfs3/file.c
> +++ b/fs/ntfs3/file.c
> @@ -347,7 +347,7 @@ static int ntfs_file_mmap_prepare(struct vm_area_desc *desc)
> struct inode *inode = file_inode(file);
> struct ntfs_inode *ni = ntfs_i(inode);
> u64 from = ((u64)desc->pgoff << PAGE_SHIFT);
> - bool rw = desc->vm_flags & VM_WRITE;
> + const bool rw = vma_desc_test_flags(desc, VMA_WRITE_BIT);
> int err;
>
> /* Avoid any operation if inode is bad. */
> diff --git a/fs/orangefs/file.c b/fs/orangefs/file.c
> index 919f99b16834..c75aa3f419b1 100644
> --- a/fs/orangefs/file.c
> +++ b/fs/orangefs/file.c
> @@ -411,8 +411,8 @@ static int orangefs_file_mmap_prepare(struct vm_area_desc *desc)
> "orangefs_file_mmap: called on %pD\n", file);
>
> /* set the sequential readahead hint */
> - desc->vm_flags |= VM_SEQ_READ;
> - desc->vm_flags &= ~VM_RAND_READ;
> + vma_desc_set_flags(desc, VMA_SEQ_READ_BIT);
> + vma_desc_clear_flags(desc, VMA_RAND_READ_BIT);
>
> file_accessed(file);
> desc->vm_ops = &orangefs_file_vm_ops;
> diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
> index 77b8ca2757e0..0f8e838ece07 100644
> --- a/fs/ramfs/file-nommu.c
> +++ b/fs/ramfs/file-nommu.c
> @@ -264,7 +264,7 @@ static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
> */
> static int ramfs_nommu_mmap_prepare(struct vm_area_desc *desc)
> {
> - if (!is_nommu_shared_mapping(desc->vm_flags))
> + if (!is_nommu_shared_vma_flags(&desc->vma_flags))
> return -ENOSYS;
>
> file_accessed(desc->file);
> diff --git a/fs/resctrl/pseudo_lock.c b/fs/resctrl/pseudo_lock.c
> index 0bfc13c5b96d..e81d71abfe54 100644
> --- a/fs/resctrl/pseudo_lock.c
> +++ b/fs/resctrl/pseudo_lock.c
> @@ -1044,7 +1044,7 @@ static int pseudo_lock_dev_mmap_prepare(struct vm_area_desc *desc)
> * Ensure changes are carried directly to the memory being mapped,
> * do not allow copy-on-write mapping.
> */
> - if (!(desc->vm_flags & VM_SHARED)) {
> + if (!vma_desc_test_flags(desc, VMA_SHARED_BIT)) {
> mutex_unlock(&rdtgroup_mutex);
> return -EINVAL;
> }
> diff --git a/fs/romfs/mmap-nommu.c b/fs/romfs/mmap-nommu.c
> index 4b77c6dc4418..7c3a1a7fecee 100644
> --- a/fs/romfs/mmap-nommu.c
> +++ b/fs/romfs/mmap-nommu.c
> @@ -63,7 +63,7 @@ static unsigned long romfs_get_unmapped_area(struct file *file,
> */
> static int romfs_mmap_prepare(struct vm_area_desc *desc)
> {
> - return is_nommu_shared_mapping(desc->vm_flags) ? 0 : -ENOSYS;
> + return is_nommu_shared_vma_flags(&desc->vma_flags) ? 0 : -ENOSYS;
> }
>
> static unsigned romfs_mmap_capabilities(struct file *file)
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 7874cf745af3..1238ec018bc7 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1974,14 +1974,14 @@ xfs_file_mmap_prepare(
> * We don't support synchronous mappings for non-DAX files and
> * for DAX files if underneath dax_device is not synchronous.
> */
> - if (!daxdev_mapping_supported(desc->vm_flags, file_inode(file),
> + if (!daxdev_mapping_supported(desc, file_inode(file),
> target->bt_daxdev))
> return -EOPNOTSUPP;
>
> file_accessed(file);
> desc->vm_ops = &xfs_file_vm_ops;
> if (IS_DAX(inode))
> - desc->vm_flags |= VM_HUGEPAGE;
> + vma_desc_set_flags(desc, VMA_HUGEPAGE_BIT);
> return 0;
> }
>
> diff --git a/fs/zonefs/file.c b/fs/zonefs/file.c
> index c1e5e30e90a0..8a7161fc49e5 100644
> --- a/fs/zonefs/file.c
> +++ b/fs/zonefs/file.c
> @@ -333,7 +333,8 @@ static int zonefs_file_mmap_prepare(struct vm_area_desc *desc)
> * ordering between msync() and page cache writeback.
> */
> if (zonefs_inode_is_seq(file_inode(file)) &&
> - (desc->vm_flags & VM_SHARED) && (desc->vm_flags & VM_MAYWRITE))
> + vma_desc_test_flags(desc, VMA_SHARED_BIT) &&
> + vma_desc_test_flags(desc, VMA_MAYWRITE_BIT))
> return -EINVAL;
>
> file_accessed(file);
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index 9d624f4d9df6..bf103f317cac 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -65,11 +65,11 @@ size_t dax_recovery_write(struct dax_device *dax_dev, pgoff_t pgoff,
> /*
> * Check if given mapping is supported by the file / underlying device.
> */
> -static inline bool daxdev_mapping_supported(vm_flags_t vm_flags,
> +static inline bool daxdev_mapping_supported(const struct vm_area_desc *desc,
> const struct inode *inode,
> struct dax_device *dax_dev)
> {
> - if (!(vm_flags & VM_SYNC))
> + if (!vma_desc_test_flags(desc, VMA_SYNC_BIT))
> return true;
> if (!IS_DAX(inode))
> return false;
> @@ -111,11 +111,11 @@ static inline void set_dax_nomc(struct dax_device *dax_dev)
> static inline void set_dax_synchronous(struct dax_device *dax_dev)
> {
> }
> -static inline bool daxdev_mapping_supported(vm_flags_t vm_flags,
> +static inline bool daxdev_mapping_supported(const struct vm_area_desc *desc,
> const struct inode *inode,
> struct dax_device *dax_dev)
> {
> - return !(vm_flags & VM_SYNC);
> + return !vma_desc_test_flags(desc, VMA_SYNC_BIT);
> }
> static inline size_t dax_recovery_write(struct dax_device *dax_dev,
> pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index fd93317193e0..e31f72a021ef 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -550,17 +550,18 @@ enum {
> /*
> * Physically remapped pages are special. Tell the
> * rest of the world about it:
> - * VM_IO tells people not to look at these pages
> + * IO tells people not to look at these pages
> * (accesses can have side effects).
> - * VM_PFNMAP tells the core MM that the base pages are just
> + * PFNMAP tells the core MM that the base pages are just
> * raw PFN mappings, and do not have a "struct page" associated
> * with them.
> - * VM_DONTEXPAND
> + * DONTEXPAND
> * Disable vma merging and expanding with mremap().
> - * VM_DONTDUMP
> + * DONTDUMP
> * Omit vma from core dump, even when VM_IO turned off.
> */

I don't think it's useful to erase the VM_ prefix off the flags. These still
exist, so maybe the alternative would be to rename them to e.g VMA_IO in
comments, etc. I think just saying "IO" or "the I/O flag" above is ambiguous.

> -#define VM_REMAP_FLAGS (VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)
> +#define VMA_REMAP_FLAGS mk_vma_flags(VMA_IO_BIT, VMA_PFNMAP_BIT, \
> + VMA_DONTEXPAND_BIT, VMA_DONTDUMP_BIT)

as a sidenote, these flags are no longer constant expressions and thus

static vma_flags_t flags = VMA_REMAP_FLAGS;

can't compile.

Rest LGTM though.

Acked-by: Pedro Falcato <pfalcato@suse.de>

--
Pedro