Re: [PATCH v4 06/10] mmap locking API: convert nested write lock sites

[Matthew Wilcox]

On Tue, Apr 14, 2020 at 05:43:49PM -0700, Michel Lespinasse wrote:
> @@ -47,7 +48,7 @@ static inline void activate_mm(struct mm_struct *old, struct mm_struct *new)
>  	 * when the new ->mm is used for the first time.
>  	 */
>  	__switch_mm(&new->context.id);
> -	down_write_nested(&new->mmap_sem, 1);
> +	mmap_write_lock_nested(new, 1);

This should have already been using SINGLE_DEPTH_NESTING.  1 is
uninformative.