[PATCH] fs/dax: Remove redundant deferred list initialization

[PATCH] fs/dax: Remove redundant deferred list initialization

[Kaitao Cheng]

From: Kaitao Cheng <chengkaitao@kylinos.cn>

prep_compound_page() calls prep_compound_head(), which initializes
folio->_deferred_list for compound folios with an order greater than one.
Therefore, dax_folio_init() initializes the list twice for large DAX
folios.

Remove the redundant initialization from dax_folio_init(). This leaves
the behavior unchanged and keeps compound folio initialization
centralized in prep_compound_head().

Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
---
 fs/dax.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 6ba50142eeb2..dad4efea7964 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -469,8 +469,6 @@ static void dax_folio_init(void *entry)
 
 	if (order > 0) {
 		prep_compound_page(&folio->page, order);
-		if (order > 1)
-			INIT_LIST_HEAD(&folio->_deferred_list);
 		WARN_ON_ONCE(folio_ref_count(folio));
 	}
 }
-- 
2.50.1 (Apple Git-155)

Re: [PATCH] fs/dax: Remove redundant deferred list initialization

[Muchun Song]

> On Sep 3, 2026, at 13:02, Kaitao Cheng <kaitao.cheng@linux.dev> wrote:
> 
> From: Kaitao Cheng <chengkaitao@kylinos.cn>
> 
> prep_compound_page() calls prep_compound_head(), which initializes
> folio->_deferred_list for compound folios with an order greater than one.
> Therefore, dax_folio_init() initializes the list twice for large DAX
> folios.
> 
> Remove the redundant initialization from dax_folio_init(). This leaves
> the behavior unchanged and keeps compound folio initialization
> centralized in prep_compound_head().
> 
> Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>

Acked-by: Muchun Song <muchun.song@linux.dev>

Thanks.

Re: [PATCH] fs/dax: Remove redundant deferred list initialization

[Christian Brauner]

On Thu, 03 Sep 2026 13:02:07 +0800, Kaitao Cheng wrote:
> fs/dax: Remove redundant deferred list initialization

Applied to the vfs-7.4.misc branch of the vfs/vfs.git tree.
Patches in the vfs-7.4.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs-7.4.misc

[1/1] fs/dax: Remove redundant deferred list initialization
      https://git.kernel.org/vfs/vfs/c/4dda2f40edd8