+ nilfs2-eliminate-staggered-calls-to-kunmap-in-nilfs_rename.patch added to mm-nonmm-unstable branch

+ nilfs2-eliminate-staggered-calls-to-kunmap-in-nilfs_rename.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: nilfs2: eliminate staggered calls to kunmap in nilfs_rename
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     nilfs2-eliminate-staggered-calls-to-kunmap-in-nilfs_rename.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/nilfs2-eliminate-staggered-calls-to-kunmap-in-nilfs_rename.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Subject: nilfs2: eliminate staggered calls to kunmap in nilfs_rename
Date: Mon, 27 Nov 2023 23:30:21 +0900

In nilfs_rename(), calls to nilfs_put_page() to release pages obtained
with nilfs_find_entry() or nilfs_dotdot() are alternated in the normal
path.

When replacing the kernel memory mapping method from kmap to
kmap_local_{page,folio}, this violates the constraint on the calling order
of kunmap_local().

Swap the order of nilfs_put_page calls where the kmap sections of multiple
pages overlap so that they are nested, allowing direct replacement of
nilfs_put_page() -> unmap_and_put_page().

Without this reordering, that replacement will cause a kernel WARNING in
kunmap_local_indexed() on architectures with high memory mapping.

Link: https://lkml.kernel.org/r/20231127143036.2425-3-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/nilfs2/namei.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/nilfs2/namei.c~nilfs2-eliminate-staggered-calls-to-kunmap-in-nilfs_rename
+++ a/fs/nilfs2/namei.c
@@ -411,13 +411,14 @@ static int nilfs_rename(struct mnt_idmap
 	inode_set_ctime_current(old_inode);
 
 	nilfs_delete_entry(old_de, old_page);
-	nilfs_put_page(old_page);
 
 	if (dir_de) {
 		nilfs_set_link(old_inode, dir_de, dir_page, new_dir);
 		nilfs_put_page(dir_page);
 		drop_nlink(old_dir);
 	}
+	nilfs_put_page(old_page);
+
 	nilfs_mark_inode_dirty(old_dir);
 	nilfs_mark_inode_dirty(old_inode);
 
_

Patches currently in -mm which might be from konishi.ryusuke@gmail.com are

nilfs2-move-page-release-outside-of-nilfs_delete_entry-and-nilfs_set_link.patch
nilfs2-eliminate-staggered-calls-to-kunmap-in-nilfs_rename.patch