linux-kernel - Re: [PATCH 3/4] mm, swap: cleanup swap entry allocation parameter

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Message-ID: <CAMgjq7DGy_ZmPqcqUO6s5BN381Zuee_g3KWjVqM3amLhpwE=2g@mail.gmail.com>
Date: Tue, 7 Oct 2025 04:07:44 +0800
From: Kairui Song <ryncsn@...il.com>
To: linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>, Kemeng Shi <shikemeng@...weicloud.com>, 
	Nhat Pham <nphamcs@...il.com>, Baoquan He <bhe@...hat.com>, Barry Song <baohua@...nel.org>, 
	Chris Li <chrisl@...nel.org>, Baolin Wang <baolin.wang@...ux.alibaba.com>, 
	David Hildenbrand <david@...hat.com>, "Matthew Wilcox (Oracle)" <willy@...radead.org>, 
	Ying Huang <ying.huang@...ux.alibaba.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] mm, swap: cleanup swap entry allocation parameter

On Tue, Oct 7, 2025 at 4:03 AM Kairui Song <ryncsn@...il.com> wrote:
>
> From: Kairui Song <kasong@...cent.com>
>
> We no longer need this GFP parameter after commit 8578e0c00dcf ("mm, swap:
> use the swap table for the swap cache and switch API"). Before that
> commit the GFP parameter is already almost identical for all callers, so
> nothing changed by that commit. Swap table just moved the GFP to lower
> layer and make it more defined and changes depend on atomic or sleep
> allocation.
>
> Now this parameter is no longer used, just remove it. No behavior
> change.
>
> Signed-off-by: Kairui Song <kasong@...cent.com>
> ---
>  include/linux/swap.h | 4 ++--
>  mm/shmem.c           | 2 +-
>  mm/swapfile.c        | 2 +-
>  mm/vmscan.c          | 4 ++--
>  4 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index e818fbade1e2..a4b264817735 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -462,7 +462,7 @@ static inline long get_nr_swap_pages(void)
>  }
>
>  extern void si_swapinfo(struct sysinfo *);
> -int folio_alloc_swap(struct folio *folio, gfp_t gfp_mask);
> +int folio_alloc_swap(struct folio *folio);
>  bool folio_free_swap(struct folio *folio);
>  void put_swap_folio(struct folio *folio, swp_entry_t entry);
>  extern swp_entry_t get_swap_page_of_type(int);
> @@ -560,7 +560,7 @@ static inline int swp_swapcount(swp_entry_t entry)
>         return 0;
>  }
>
> -static inline int folio_alloc_swap(struct folio *folio, gfp_t gfp_mask)
> +static inline int folio_alloc_swap(struct folio *folio)
>  {
>         return -EINVAL;
>  }
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 45f51745ad88..63092cc0b141 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1617,7 +1617,7 @@ int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
>                 folio_mark_uptodate(folio);
>         }
>
> -       if (!folio_alloc_swap(folio, __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN)) {
> +       if (!folio_alloc_swap(folio)) {
>                 bool first_swapped = shmem_recalc_inode(inode, 0, nr_pages);
>                 int error;
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 732e07c70ce9..534b21aeef5a 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1425,7 +1425,7 @@ static bool swap_sync_discard(void)
>   * Context: Caller needs to hold the folio lock.
>   * Return: Whether the folio was added to the swap cache.
>   */
> -int folio_alloc_swap(struct folio *folio, gfp_t gfp)
> +int folio_alloc_swap(struct folio *folio)
>  {
>         unsigned int order = folio_order(folio);
>         unsigned int size = 1 << order;

One trivial issue for myself, I better update the kerneldoc too...
sorry about this:

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 534b21aeef5a..0c2174d6b924 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1417,7 +1417,6 @@ static bool swap_sync_discard(void)
 /**
  * folio_alloc_swap - allocate swap space for a folio
  * @folio: folio we want to move to swap
- * @gfp: gfp mask for shadow nodes
  *
  * Allocate swap space for the folio and add the folio to the
  * swap cache.