Re: [PATCH v2 02/15] mm: pgtable: introduce generic p4d_alloc_one() and p4d_free()

[Alexander Gordeev]

On Wed, Dec 18, 2024 at 09:04:38PM +0800, Qi Zheng wrote:
> For these architectures, provide a generic implementation in
> asm-generic/pgalloc.h and convert them to use it. And like other levels
> of page tables, add statistics for P4D level page table.

FWIW, introducing the generic implementation and adding ctor|dtors
look as separate changes to me.

...
>  static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)
>  {
> -	if (!pgtable_l5_enabled())
> -		return;
> -	BUG_ON((unsigned long)p4d & (PAGE_SIZE-1));

Or maybe?

	BUG_ON(!IS_ALIGNED((unsigned long)p4d, PAGE_SIZE));

> -	free_page((unsigned long)p4d);
> +	if (pgtable_l5_enabled())
> +		__p4d_free(mm, p4d);
>  }