Re: [PATCH v2 07/13] mm: update secretmem to use VMA flags on mmap_prepare

Liam R. Howlett
2026-02-09T19:09:19Z

* Lorenzo Stoakes <lorenzo.stoakes@oracle.com> [260122 16:06]:
> This patch updates secretmem to use the new vma_flags_t type which will
> soon supersede vm_flags_t altogether.
>
> In order to make this change we also have to update mlock_future_ok(), we
> replace the vm_flags_t parameter with a simple boolean is_vma_locked one,
> which also simplifies the invocation here.
>
> This is laying the groundwork for eliminating the vm_flags_t in
> vm_area_desc and more broadly throughout the kernel.
>
> No functional changes intended.
>
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

With the type fix for brk - I assume sparse would have detected this as
well.

Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>

> ---
> mm/internal.h | 2 +-
> mm/mmap.c | 8 ++++----
> mm/mremap.c | 2 +-
> mm/secretmem.c | 7 +++----
> mm/vma.c | 2 +-
> 5 files changed, 10 insertions(+), 11 deletions(-)
>
> diff --git a/mm/internal.h b/mm/internal.h
> index ef71a1d9991f..d67e8bb75734 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -1046,7 +1046,7 @@ extern long populate_vma_page_range(struct vm_area_struct *vma,
> unsigned long start, unsigned long end, int *locked);
> extern long faultin_page_range(struct mm_struct *mm, unsigned long start,
> unsigned long end, bool write, int *locked);
> -bool mlock_future_ok(const struct mm_struct *mm, vm_flags_t vm_flags,
> +bool mlock_future_ok(const struct mm_struct *mm, bool is_vma_locked,
> unsigned long bytes);
>
> /*
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 038ff5f09df0..354479c95896 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -225,12 +225,12 @@ static inline unsigned long round_hint_to_min(unsigned long hint)
> return hint;
> }
>
> -bool mlock_future_ok(const struct mm_struct *mm, vm_flags_t vm_flags,
> - unsigned long bytes)
> +bool mlock_future_ok(const struct mm_struct *mm, bool is_vma_locked,
> + unsigned long bytes)
> {
> unsigned long locked_pages, limit_pages;
>
> - if (!(vm_flags & VM_LOCKED) || capable(CAP_IPC_LOCK))
> + if (!is_vma_locked || capable(CAP_IPC_LOCK))
> return true;
>
> locked_pages = bytes >> PAGE_SHIFT;
> @@ -416,7 +416,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
> if (!can_do_mlock())
> return -EPERM;
>
> - if (!mlock_future_ok(mm, vm_flags, len))
> + if (!mlock_future_ok(mm, vm_flags & VM_LOCKED, len))
> return -EAGAIN;
>
> if (file) {
> diff --git a/mm/mremap.c b/mm/mremap.c
> index 8391ae17de64..2be876a70cc0 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -1740,7 +1740,7 @@ static int check_prep_vma(struct vma_remap_struct *vrm)
> if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
> return -EFAULT;
>
> - if (!mlock_future_ok(mm, vma->vm_flags, vrm->delta))
> + if (!mlock_future_ok(mm, vma->vm_flags & VM_LOCKED, vrm->delta))
> return -EAGAIN;
>
> if (!may_expand_vm(mm, vma->vm_flags, vrm->delta >> PAGE_SHIFT))
> diff --git a/mm/secretmem.c b/mm/secretmem.c
> index edf111e0a1bb..11a779c812a7 100644
> --- a/mm/secretmem.c
> +++ b/mm/secretmem.c
> @@ -122,13 +122,12 @@ static int secretmem_mmap_prepare(struct vm_area_desc *desc)
> {
> const unsigned long len = vma_desc_size(desc);
>
> - if ((desc->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
> + if (!vma_desc_test_flags(desc, VMA_SHARED_BIT, VMA_MAYSHARE_BIT))
> return -EINVAL;
>
> - if (!mlock_future_ok(desc->mm, desc->vm_flags | VM_LOCKED, len))
> + vma_desc_set_flags(desc, VMA_LOCKED_BIT, VMA_DONTDUMP_BIT);
> + if (!mlock_future_ok(desc->mm, /*is_vma_locked=*/ true, len))
> return -EAGAIN;
> -
> - desc->vm_flags |= VM_LOCKED | VM_DONTDUMP;
> desc->vm_ops = &secretmem_vm_ops;
>
> return 0;
> diff --git a/mm/vma.c b/mm/vma.c
> index f352d5c72212..39dcd9ddd4ba 100644
> --- a/mm/vma.c
> +++ b/mm/vma.c
> @@ -3053,7 +3053,7 @@ static int acct_stack_growth(struct vm_area_struct *vma,
> return -ENOMEM;
>
> /* mlock limit tests */
> - if (!mlock_future_ok(mm, vma->vm_flags, grow << PAGE_SHIFT))
> + if (!mlock_future_ok(mm, vma->vm_flags & VM_LOCKED, grow << PAGE_SHIFT))
> return -ENOMEM;
>
> /* Check to ensure the stack will not grow into a hugetlb-only region */
> --
> 2.52.0
>