linux-kernel - Re: [RFC v2 08/14] mm: do not split a folio if it has minimum folio order requirement

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Date: Tue, 13 Feb 2024 16:02:20 +0100
From: Hannes Reinecke <hare@...e.de>
To: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>,
 linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc: mcgrof@...nel.org, gost.dev@...sung.com, akpm@...ux-foundation.org,
 kbusch@...nel.org, djwong@...nel.org, chandan.babu@...cle.com,
 p.raghav@...sung.com, linux-kernel@...r.kernel.org, willy@...radead.org,
 linux-mm@...ck.org, david@...morbit.com
Subject: Re: [RFC v2 08/14] mm: do not split a folio if it has minimum folio
 order requirement

On 2/13/24 10:37, Pankaj Raghav (Samsung) wrote:
> From: Pankaj Raghav <p.raghav@...sung.com>
> 
> As we don't have a way to split a folio to a any given lower folio
> order yet, avoid splitting the folio in split_huge_page_to_list() if it
> has a minimum folio order requirement.
> 
> Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
> Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
> ---
>   mm/huge_memory.c | 13 +++++++++++++
>   1 file changed, 13 insertions(+)
> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 94c958f7ebb5..d897efc51025 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -3026,6 +3026,19 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
>   			goto out;
>   		}
>   
> +		/*
> +		 * Do not split if mapping has minimum folio order
> +		 * requirement.
> +		 *
> +		 * XXX: Once we have support for splitting to any lower
> +		 * folio order, then it could be split based on the
> +		 * min_folio_order.
> +		 */
> +		if (mapping_min_folio_order(mapping)) {
> +			ret = -EAGAIN;
> +			goto out;
> +		}
> +
>   		gfp = current_gfp_context(mapping_gfp_mask(mapping) &
>   							GFP_RECLAIM_MASK);
>   
Reviewed-by: Hannes Reinecke <hare@...e.de>

Cheers,

Hannes