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19aa667ace
syzbot detected a circular locking dependency. the scenarios:
CPU0 CPU1
---- ----
lock(&ocfs2_quota_ip_alloc_sem_key);
lock(&ocfs2_sysfile_lock_key[USER_QUOTA_SYSTEM_INODE]);
lock(&ocfs2_quota_ip_alloc_sem_key);
lock(&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]);
or:
CPU0 CPU1
---- ----
lock(&ocfs2_quota_ip_alloc_sem_key);
lock(&dquot->dq_lock);
lock(&ocfs2_quota_ip_alloc_sem_key);
lock(&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]);
Following are the code paths for above scenarios:
path_openat
ocfs2_create
ocfs2_mknod
+ ocfs2_reserve_new_inode
| ocfs2_reserve_suballoc_bits
| inode_lock(alloc_inode) //C0: hold INODE_ALLOC_SYSTEM_INODE
| //ocfs2_free_alloc_context(inode_ac) is called at the end of
| //caller ocfs2_mknod to handle the release
|
+ ocfs2_get_init_inode
__dquot_initialize
dqget
ocfs2_acquire_dquot
+ ocfs2_lock_global_qf
| down_write(&OCFS2_I(oinfo->dqi_gqinode)->ip_alloc_sem)//A2:grabbing
+ ocfs2_create_local_dquot
down_write(&OCFS2_I(lqinode)->ip_alloc_sem)//A3:grabbing
evict
ocfs2_evict_inode
ocfs2_delete_inode
ocfs2_wipe_inode
+ inode_lock(orphan_dir_inode) //B0:hold
+ ...
+ ocfs2_remove_inode
inode_lock(inode_alloc_inode) //INODE_ALLOC_SYSTEM_INODE
down_write(&inode->i_rwsem) //C1:grabbing
generic_file_direct_write
ocfs2_direct_IO
__blockdev_direct_IO
dio_complete
ocfs2_dio_end_io
ocfs2_dio_end_io_write
+ down_write(&oi->ip_alloc_sem) //A0:hold
+ ocfs2_del_inode_from_orphan
inode_lock(orphan_dir_inode) //B1:grabbing
Root cause for the circular locking:
DIO completion path:
holds oi->ip_alloc_sem and is trying to acquire the orphan_dir_inode lock.
evict path:
holds the orphan_dir_inode lock and is trying to acquire the
inode_alloc_inode lock.
ocfs2_mknod path:
Holds the inode_alloc_inode lock (to allocate a new quota file) and is
blocked waiting for oi->ip_alloc_sem in ocfs2_acquire_dquot().
How to fix:
Replace down_write() with down_write_trylock() in ocfs2_acquire_dquot().
If acquiring oi->ip_alloc_sem fails, return -EBUSY to abort the file
creation routine and break the deadlock.
Link: https://lkml.kernel.org/r/20260302061707.7092-1-heming.zhao@suse.com
Signed-off-by: Heming Zhao <heming.zhao@suse.com>
Reported-by: syzbot+78359d5fbb04318c35e9@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=78359d5fbb04318c35e9
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Heming Zhao <heming.zhao@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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