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

[Michal Hocko]

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@xxxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxxx>

> ---
>  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