The patch titled
Subject: nilfs2: fix kernel bug due to missing clearing of buffer delay flag
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
nilfs2-fix-kernel-bug-due-to-missing-clearing-of-buffer-delay-flag.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/nilfs2-fix-kernel-bug-due-to-missing-clearing-of-buffer-delay-flag.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Subject: nilfs2: fix kernel bug due to missing clearing of buffer delay flag
Date: Wed, 16 Oct 2024 06:32:07 +0900
Syzbot reported that after nilfs2 reads a corrupted file system image and
degrades to read-only, the BUG_ON check for the buffer delay flag in
submit_bh_wbc() may fail, causing a kernel bug.
This is because the buffer delay flag is not cleared when clearing the
buffer state flags to discard a page/folio or a buffer head. So, fix
this.
This became necessary when the use of nilfs2's own page clear routine was
expanded. This state inconsistency does not occur if the buffer is
written normally by log writing.
Link: https://lkml.kernel.org/r/20241015213300.7114-1-konishi.ryusuke@xxxxxxxxx
Fixes: 8c26c4e2694a ("nilfs2: fix issue with flush kernel thread after remount in RO mode because of driver's internal error or metadata corruption")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Reported-by: syzbot+985ada84bf055a575c07@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=985ada84bf055a575c07
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/nilfs2/page.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/fs/nilfs2/page.c~nilfs2-fix-kernel-bug-due-to-missing-clearing-of-buffer-delay-flag
+++ a/fs/nilfs2/page.c
@@ -77,7 +77,8 @@ void nilfs_forget_buffer(struct buffer_h
const unsigned long clear_bits =
(BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
- BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
+ BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected) |
+ BIT(BH_Delay));
lock_buffer(bh);
set_mask_bits(&bh->b_state, clear_bits, 0);
@@ -406,7 +407,8 @@ void nilfs_clear_folio_dirty(struct foli
const unsigned long clear_bits =
(BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
- BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
+ BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected) |
+ BIT(BH_Delay));
bh = head;
do {
_
Patches currently in -mm which might be from konishi.ryusuke@xxxxxxxxx are
nilfs2-propagate-directory-read-errors-from-nilfs_find_entry.patch
nilfs2-fix-kernel-bug-due-to-missing-clearing-of-buffer-delay-flag.patch
