======================================================
WARNING: possible circular locking dependency detected
5.9.0-rc3-next-20200903-syzkaller #0 Not tainted
------------------------------------------------------
kworker/u4:2/25 is trying to acquire lock:
ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: flush_workqueue+0xe1/0x13e0 kernel/workqueue.c:2777
but task is already holding lock:
ffffffff8a87d730 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x9b/0xb10 net/core/net_namespace.c:565
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (pernet_ops_rwsem){++++}-{3:3}:
down_write+0x8d/0x150 kernel/locking/rwsem.c:1531
unregister_netdevice_notifier+0x1e/0x170 net/core/dev.c:1861
raw_release+0x58/0x890 net/can/raw.c:354
__sock_release+0xcd/0x280 net/socket.c:596
sock_close+0x18/0x20 net/socket.c:1277
__fput+0x285/0x920 fs/file_table.c:281
task_work_run+0xdd/0x190 kernel/task_work.c:141
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop kernel/entry/common.c:140 [inline]
exit_to_user_mode_prepare+0x1e1/0x200 kernel/entry/common.c:167
syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:242
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #2 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}:
down_write+0x8d/0x150 kernel/locking/rwsem.c:1531
inode_lock include/linux/fs.h:779 [inline]
__sock_release+0x86/0x280 net/socket.c:595
sock_close+0x18/0x20 net/socket.c:1277
__fput+0x285/0x920 fs/file_table.c:281
delayed_fput+0x56/0x70 fs/file_table.c:309
process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
kthread+0x3b5/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
-> #1 ((delayed_fput_work).work){+.+.}-{0:0}:
process_one_work+0x8bb/0x1670 kernel/workqueue.c:2245
worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
kthread+0x3b5/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
-> #0 ((wq_completion)events){+.+.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:2496 [inline]
check_prevs_add kernel/locking/lockdep.c:2601 [inline]
validate_chain kernel/locking/lockdep.c:3218 [inline]
__lock_acquire+0x29bb/0x5570 kernel/locking/lockdep.c:4426
lock_acquire+0x1f3/0xae0 kernel/locking/lockdep.c:5006
flush_workqueue+0x110/0x13e0 kernel/workqueue.c:2780
flush_scheduled_work include/linux/workqueue.h:597 [inline]
tipc_exit_net+0x47/0x2a0 net/tipc/core.c:116
ops_exit_list+0xb0/0x160 net/core/net_namespace.c:186
cleanup_net+0x4ea/0xb10 net/core/net_namespace.c:603
process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
kthread+0x3b5/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
other info that might help us debug this:
Chain exists of:
(wq_completion)events --> &sb->s_type->i_mutex_key#12 --> pernet_ops_rwsem
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(pernet_ops_rwsem);
lock(&sb->s_type->i_mutex_key#12);
lock(pernet_ops_rwsem);
lock((wq_completion)events);
*** DEADLOCK ***
3 locks held by kworker/u4:2/25:
#0: ffff8880a97b9138 ((wq_completion)netns){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff8880a97b9138 ((wq_completion)netns){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
#0: ffff8880a97b9138 ((wq_completion)netns){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
#0: ffff8880a97b9138 ((wq_completion)netns){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
#0: ffff8880a97b9138 ((wq_completion)netns){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
#0: ffff8880a97b9138 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x82b/0x1670 kernel/workqueue.c:2240
#1: ffffc90000e27da8 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x85f/0x1670 kernel/workqueue.c:2244
#2: ffffffff8a87d730 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x9b/0xb10 net/core/net_namespace.c:565
stack backtrace:
CPU: 0 PID: 25 Comm: kworker/u4:2 Not tainted 5.9.0-rc3-next-20200903-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x198/0x1fd lib/dump_stack.c:118
check_noncircular+0x324/0x3e0 kernel/locking/lockdep.c:1827
check_prev_add kernel/locking/lockdep.c:2496 [inline]
check_prevs_add kernel/locking/lockdep.c:2601 [inline]
validate_chain kernel/locking/lockdep.c:3218 [inline]
__lock_acquire+0x29bb/0x5570 kernel/locking/lockdep.c:4426
lock_acquire+0x1f3/0xae0 kernel/locking/lockdep.c:5006
flush_workqueue+0x110/0x13e0 kernel/workqueue.c:2780
flush_scheduled_work include/linux/workqueue.h:597 [inline]
tipc_exit_net+0x47/0x2a0 net/tipc/core.c:116
ops_exit_list+0xb0/0x160 net/core/net_namespace.c:186
cleanup_net+0x4ea/0xb10 net/core/net_namespace.c:603
process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
kthread+0x3b5/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
tipc: TX() has been purged, node left!