Re: [RFC PATCH 09/11] shmem: add order arg to shmem_alloc_folio()

[Hannes Reinecke]

On 10/28/23 23:15, Daniel Gomez wrote:
> Add folio order argument to the shmem_alloc_folio() and merge it with
> the shmem_alloc_folio_huge(). Return will make use of the new
> page_rmappable_folio() where order-0 and high order folios are
> both supported.
>
> Signed-off-by: Daniel Gomez <da.gomez@xxxxxxxxxxx>
> ---
>   mm/shmem.c | 33 ++++++++++-----------------------
>   1 file changed, 10 insertions(+), 23 deletions(-)
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index d8dc2ceaba18..fc7605da4316 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1614,40 +1614,27 @@ static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
>   	return result;
>   }
>   
> -static struct folio *shmem_alloc_hugefolio(gfp_t gfp,
> -		struct shmem_inode_info *info, pgoff_t index)
> +static struct folio *shmem_alloc_folio(gfp_t gfp, struct shmem_inode_info *info,
> +				       pgoff_t index, unsigned int order)
>   {
>   	struct mempolicy *mpol;
>   	pgoff_t ilx;
>   	struct page *page;
>   
> -	mpol = shmem_get_pgoff_policy(info, index, HPAGE_PMD_ORDER, &ilx);
> -	page = alloc_pages_mpol(gfp, HPAGE_PMD_ORDER, mpol, ilx, numa_node_id());
> +	mpol = shmem_get_pgoff_policy(info, index, order, &ilx);
> +	page = alloc_pages_mpol(gfp, order, mpol, ilx, numa_node_id());
>   	mpol_cond_put(mpol);
>   
>   	return page_rmappable_folio(page);
>   }
>   
> -static struct folio *shmem_alloc_folio(gfp_t gfp,
> -		struct shmem_inode_info *info, pgoff_t index)
> -{
> -	struct mempolicy *mpol;
> -	pgoff_t ilx;
> -	struct page *page;
> -
> -	mpol = shmem_get_pgoff_policy(info, index, 0, &ilx);
> -	page = alloc_pages_mpol(gfp, 0, mpol, ilx, numa_node_id());
> -	mpol_cond_put(mpol);
> -
> -	return (struct folio *)page;
> -}
> -
>   static struct folio *shmem_alloc_and_add_folio(gfp_t gfp,
>   		struct inode *inode, pgoff_t index,
>   		struct mm_struct *fault_mm, size_t len)
>   {
>   	struct address_space *mapping = inode->i_mapping;
>   	struct shmem_inode_info *info = SHMEM_I(inode);
> +	unsigned int order = 0;
>   	struct folio *folio;
>   	long pages;
>   	int error;
> @@ -1668,12 +1655,12 @@ static struct folio *shmem_alloc_and_add_folio(gfp_t gfp,
>   				index + HPAGE_PMD_NR - 1, XA_PRESENT))
>   			return ERR_PTR(-E2BIG);
>   
> -		folio = shmem_alloc_hugefolio(gfp, info, index);
> +		folio = shmem_alloc_folio(gfp, info, index, HPAGE_PMD_ORDER);
>   		if (!folio)
>   			count_vm_event(THP_FILE_FALLBACK);
>   	} else {
> -		pages = 1;
> -		folio = shmem_alloc_folio(gfp, info, index);
> +		pages = 1UL << order;
> +		folio = shmem_alloc_folio(gfp, info, index, order);
>   	}
>   	if (!folio)
>   		return ERR_PTR(-ENOMEM);
> @@ -1774,7 +1761,7 @@ static int shmem_replace_folio(struct folio **foliop, gfp_t gfp,
>   	 */
>   	gfp &= ~GFP_CONSTRAINT_MASK;
>   	VM_BUG_ON_FOLIO(folio_test_large(old), old);
> -	new = shmem_alloc_folio(gfp, info, index);
> +	new = shmem_alloc_folio(gfp, info, index, 0);

Shouldn't you use folio_order(old) here?

Cheers,

Hannes
--
Dr. Hannes Reinecke                Kernel Storage Architect
hare@xxxxxxx                              +49 911 74053 688
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