4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx> commit 6ed469df0bfbef3e4b44fca954a781919db9f7ab upstream. 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. Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx> Link: https://lore.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") Reported-by: syzbot+985ada84bf055a575c07@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=985ada84bf055a575c07 Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/nilfs2/page.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/fs/nilfs2/page.c +++ b/fs/nilfs2/page.c @@ -78,7 +78,8 @@ 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); @@ -412,7 +413,8 @@ void nilfs_clear_dirty_page(struct page 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 = page_buffers(page); do {
