Re: [PATCH mm-unstable v9 14/31] s390: Convert various pgalloc functions to use ptdescs

[Heiko Carstens <hca@linux.ibm.com>]

On Mon, Aug 07, 2023 at 04:04:56PM -0700, Vishal Moola (Oracle) wrote:
> As part of the conversions to replace pgtable constructor/destructors with
> ptdesc equivalents, convert various page table functions to use ptdescs.
> 
> Some of the functions use the *get*page*() helper functions. Convert
> these to use pagetable_alloc() and ptdesc_address() instead to help
> standardize page tables further.
> 
> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> ---
>  arch/s390/include/asm/pgalloc.h |   4 +-
>  arch/s390/include/asm/tlb.h     |   4 +-
>  arch/s390/mm/pgalloc.c          | 128 ++++++++++++++++----------------
>  3 files changed, 69 insertions(+), 67 deletions(-)
...
> diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c
> index d7374add7820..07fc660a24aa 100644
> --- a/arch/s390/mm/pgalloc.c
> +++ b/arch/s390/mm/pgalloc.c
...
> @@ -488,16 +486,20 @@ static void base_pgt_free(unsigned long *table)
>  static unsigned long *base_crst_alloc(unsigned long val)
>  {
>  	unsigned long *table;
> +	struct ptdesc *ptdesc;
>  
> -	table =	(unsigned long *)__get_free_pages(GFP_KERNEL, CRST_ALLOC_ORDER);
> -	if (table)
> -		crst_table_init(table, val);
> +	ptdesc = pagetable_alloc(GFP_KERNEL & ~__GFP_HIGHMEM, CRST_ALLOC_ORDER);

I guess I must miss something, but what is the reason to mask out
__GFP_HIGHMEM here? It is not part of GFP_KERNEL, nor does s390 support
HIGHMEM.