Re: [PATCH v3 3/7] mm/mprotect: Replace can_modify_mm with can_modify_vma

["Liam R. Howlett" <Liam.Howlett@oracle.com>]

* Pedro Falcato <pedro.falcato@gmail.com> [240816 20:19]:
> Avoid taking an extra trip down the mmap tree by checking the vmas
> directly. mprotect (per POSIX) tolerates partial failure.
> 
> Signed-off-by: Pedro Falcato <pedro.falcato@gmail.com>

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

> ---
>  mm/mprotect.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index 446f8e5f10d9..0c5d6d06107d 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -611,6 +611,9 @@ mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
>  	unsigned long charged = 0;
>  	int error;
>  
> +	if (!can_modify_vma(vma))
> +		return -EPERM;
> +
>  	if (newflags == oldflags) {
>  		*pprev = vma;
>  		return 0;
> @@ -769,15 +772,6 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
>  		}
>  	}
>  
> -	/*
> -	 * checking if memory is sealed.
> -	 * can_modify_mm assumes we have acquired the lock on MM.
> -	 */
> -	if (unlikely(!can_modify_mm(current->mm, start, end))) {
> -		error = -EPERM;
> -		goto out;
> -	}
> -
>  	prev = vma_prev(&vmi);
>  	if (start > vma->vm_start)
>  		prev = vma;
> 
> -- 
> 2.46.0
>