Re: [PATCH v2 2/6] mm: replace VM_LOCKED_CLEAR_MASK with VM_LOCKED_MASK

Michal Hocko
2023-01-25T09:02:11Z

On Wed 25-01-23 00:38:47, Suren Baghdasaryan wrote:
> To simplify the usage of VM_LOCKED_CLEAR_MASK in clear_vm_flags(),
> replace it with VM_LOCKED_MASK bitmask and convert all users.
>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
> include/linux/mm.h | 4 ++--
> kernel/fork.c | 2 +-
> mm/hugetlb.c | 4 ++--
> mm/mlock.c | 6 +++---
> mm/mmap.c | 6 +++---
> mm/mremap.c | 2 +-
> 6 files changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index b71f2809caac..da62bdd627bf 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -421,8 +421,8 @@ extern unsigned int kobjsize(const void *objp);
> /* This mask defines which mm->def_flags a process can inherit its parent */
> #define VM_INIT_DEF_MASK VM_NOHUGEPAGE
>
> -/* This mask is used to clear all the VMA flags used by mlock */
> -#define VM_LOCKED_CLEAR_MASK (~(VM_LOCKED | VM_LOCKONFAULT))
> +/* This mask represents all the VMA flag bits used by mlock */
> +#define VM_LOCKED_MASK (VM_LOCKED | VM_LOCKONFAULT)
>
> /* Arch-specific flags to clear when updating VM flags on protection change */
> #ifndef VM_ARCH_CLEAR
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 6683c1b0f460..03d472051236 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -669,7 +669,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
> tmp->anon_vma = NULL;
> } else if (anon_vma_fork(tmp, mpnt))
> goto fail_nomem_anon_vma_fork;
> - tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
> + clear_vm_flags(tmp, VM_LOCKED_MASK);
> file = tmp->vm_file;
> if (file) {
> struct address_space *mapping = file->f_mapping;
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index d20c8b09890e..4ecdbad9a451 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -6973,8 +6973,8 @@ static unsigned long page_table_shareable(struct vm_area_struct *svma,
> unsigned long s_end = sbase + PUD_SIZE;
>
> /* Allow segments to share if only one is marked locked */
> - unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
> - unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
> + unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED_MASK;
> + unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED_MASK;
>
> /*
> * match the virtual addresses, permission and the alignment of the
> diff --git a/mm/mlock.c b/mm/mlock.c
> index 0336f52e03d7..5c4fff93cd6b 100644
> --- a/mm/mlock.c
> +++ b/mm/mlock.c
> @@ -497,7 +497,7 @@ static int apply_vma_lock_flags(unsigned long start, size_t len,
> if (vma->vm_start != tmp)
> return -ENOMEM;
>
> - newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
> + newflags = vma->vm_flags & ~VM_LOCKED_MASK;
> newflags |= flags;
> /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
> tmp = vma->vm_end;
> @@ -661,7 +661,7 @@ static int apply_mlockall_flags(int flags)
> struct vm_area_struct *vma, *prev = NULL;
> vm_flags_t to_add = 0;
>
> - current->mm->def_flags &= VM_LOCKED_CLEAR_MASK;
> + current->mm->def_flags &= ~VM_LOCKED_MASK;
> if (flags & MCL_FUTURE) {
> current->mm->def_flags |= VM_LOCKED;
>
> @@ -681,7 +681,7 @@ static int apply_mlockall_flags(int flags)
> for_each_vma(vmi, vma) {
> vm_flags_t newflags;
>
> - newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
> + newflags = vma->vm_flags & ~VM_LOCKED_MASK;
> newflags |= to_add;
>
> /* Ignore errors */
> diff --git a/mm/mmap.c b/mm/mmap.c
> index d4abc6feced1..323bd253b25a 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -2671,7 +2671,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
> if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
> is_vm_hugetlb_page(vma) ||
> vma = get_gate_vma(current->mm))
> - vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
> + clear_vm_flags(vma, VM_LOCKED_MASK);
> else
> mm->locked_vm += (len >> PAGE_SHIFT);
> }
> @@ -3340,8 +3340,8 @@ static struct vm_area_struct *__install_special_mapping(
> vma->vm_start = addr;
> vma->vm_end = addr + len;
>
> - vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
> - vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
> + init_vm_flags(vma, (vm_flags | mm->def_flags |
> + VM_DONTEXPAND | VM_SOFTDIRTY) & ~VM_LOCKED_MASK);
> vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
>
> vma->vm_ops = ops;
> diff --git a/mm/mremap.c b/mm/mremap.c
> index 1b3ee02bead7..35db9752cb6a 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -687,7 +687,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
>
> if (unlikely(!err && (flags & MREMAP_DONTUNMAP))) {
> /* We always clear VM_LOCKED[ONFAULT] on the old vma */
> - vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
> + clear_vm_flags(vma, VM_LOCKED_MASK);
>
> /*
> * anon_vma links of the old vma is no longer needed after its page
> --
> 2.39.1

--
Michal Hocko
SUSE Labs