From: Joseph Qi Date: Fri, 6 Mar 2026 03:22:11 +0000 (+0800) Subject: ocfs2: fix possible deadlock between unlink and dio_end_io_write X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b02da26a992db0c0e2559acbda0fc48d4a2fd337;p=thirdparty%2Fkernel%2Fstable.git ocfs2: fix possible deadlock between unlink and dio_end_io_write ocfs2_unlink takes orphan dir inode_lock first and then ip_alloc_sem, while in ocfs2_dio_end_io_write, it acquires these locks in reverse order. This creates an ABBA lock ordering violation on lock classes ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE] and ocfs2_file_ip_alloc_sem_key. Lock Chain #0 (orphan dir inode_lock -> ip_alloc_sem): ocfs2_unlink ocfs2_prepare_orphan_dir ocfs2_lookup_lock_orphan_dir inode_lock(orphan_dir_inode) <- lock A __ocfs2_prepare_orphan_dir ocfs2_prepare_dir_for_insert ocfs2_extend_dir ocfs2_expand_inline_dir down_write(&oi->ip_alloc_sem) <- Lock B Lock Chain #1 (ip_alloc_sem -> orphan dir inode_lock): ocfs2_dio_end_io_write down_write(&oi->ip_alloc_sem) <- Lock B ocfs2_del_inode_from_orphan() inode_lock(orphan_dir_inode) <- Lock A Deadlock Scenario: CPU0 (unlink) CPU1 (dio_end_io_write) ------ ------ inode_lock(orphan_dir_inode) down_write(ip_alloc_sem) down_write(ip_alloc_sem) inode_lock(orphan_dir_inode) Since ip_alloc_sem is to protect allocation changes, which is unrelated with operations in ocfs2_del_inode_from_orphan. So move ocfs2_del_inode_from_orphan out of ip_alloc_sem to fix the deadlock. Link: https://lkml.kernel.org/r/20260306032211.1016452-1-joseph.qi@linux.alibaba.com Reported-by: syzbot+67b90111784a3eac8c04@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=67b90111784a3eac8c04 Fixes: a86a72a4a4e0 ("ocfs2: take ip_alloc_sem in ocfs2_dio_get_block & ocfs2_dio_end_io_write") Signed-off-by: Joseph Qi Reviewed-by: Heming Zhao Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Joseph Qi Cc: Changwei Ge Cc: Jun Piao Cc: Signed-off-by: Andrew Morton --- diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c index 17ba79f443ee..09146b43d1f0 100644 --- a/fs/ocfs2/aops.c +++ b/fs/ocfs2/aops.c @@ -2294,8 +2294,6 @@ static int ocfs2_dio_end_io_write(struct inode *inode, goto out; } - down_write(&oi->ip_alloc_sem); - /* Delete orphan before acquire i_rwsem. */ if (dwc->dw_orphaned) { BUG_ON(dwc->dw_writer_pid != task_pid_nr(current)); @@ -2308,6 +2306,7 @@ static int ocfs2_dio_end_io_write(struct inode *inode, mlog_errno(ret); } + down_write(&oi->ip_alloc_sem); di = (struct ocfs2_dinode *)di_bh->b_data; ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);