INFO: task kworker/u8:5:7445 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:5    state:D stack:23512 pid:7445  tgid:7445  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1350
 rdma_dev_change_netns+0x39/0x300
 rdma_dev_exit_net+0x203/0x340
 ops_undo_list+0x49a/0x990
 cleanup_net+0x4d8/0x820
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 ret_from_fork_asm+0x1a/0x30
 </TASK>
INFO: task syz.2.4146:22488 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.4146      state:D stack:23976 pid:22488 tgid:22487 ppid:5816   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_timeout+0x9a/0x270
 wait_for_completion+0x2bf/0x5d0
 disable_device+0x1c6/0x320
 __ib_unregister_device+0x2cb/0x3f0
 ib_unregister_device_and_put+0xb8/0xf0
 nldev_dellink+0x2d1/0x320
 rdma_nl_rcv+0x6ae/0x980
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x505/0x830
 ___sys_sendmsg+0x21f/0x2a0
 __x64_sys_sendmsg+0x19b/0x260
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb77218f6c9
RSP: 002b:00007fb772f4d038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb7723e5fa0 RCX: 00007fb77218f6c9
RDX: 0000000000040080 RSI: 0000200000000340 RDI: 0000000000000008
RBP: 00007fb772211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb7723e6038 R14: 00007fb7723e5fa0 R15: 00007ffd44616fb8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5639:
 #0: ffff8881147cc0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900035832f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
4 locks held by kworker/u8:5/7445:
 #0: ffff888100ef7948 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000417fba0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8f2bf1b0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf7/0x820
 #3: ffff888113264700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.2.4146/22488:
 #0: ffffffff99b68938 (&rdma_nl_types[idx].sem){.+.+}-{4:4}, at: rdma_nl_rcv+0x302/0x980
 #1: ffff888113264700 (&device->unregistration_lock){+.+.}-{4:4}, at: __ib_unregister_device+0x284/0x3f0
2 locks held by syz.0.4375/23427:
 #0: ffffffff8f2bf1b0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x337/0x4e0
 #1: ffff888113264700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.3.4409/23605:
 #0: ffffffff8f2bf1b0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x337/0x4e0
 #1: ffff888113264700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.1.4479/23925:
 #0: ffffffff8f2bf1b0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x337/0x4e0
 #1: ffff888113264700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.5.4559/24281:
 #0: ffffffff8f2bf1b0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x337/0x4e0
 #1: ffff888113264700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.7.4774/25083:
 #0: ffffffff8f2bf1b0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x337/0x4e0
 #1: ffff888113264700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.6.4834/25371:
 #0: ffffffff8f4d10a8 (ioctl_mutex){+.+.}-{4:4}, at: do_vcc_ioctl+0x2fa/0x9e0
 #1: ffffffff8f2bf1b0 (pernet_ops_rwsem){++++}-{4:4}, at: register_netdevice_notifier+0x91/0x3d0
1 lock held by syz-executor/26467:
5 locks held by syz-executor/26617:
 #0: ffff888037924dc8 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x212/0x510
 #1: ffff8880379240b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x66a/0x1330
 #2: ffffffff8f436168 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xa1/0x230
 #3: ffff888174889b38 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x70/0x680
 #4: ffffffff8df43138 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730
1 lock held by syz.4.5187/26774:
 #0: ffffffff8df43138 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 34 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 nmi_cpu_backtrace+0x39e/0x3d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 watchdog+0xf60/0xfa0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 26774 Comm: syz.4.5187 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:lock_release+0x44/0x3e0
Code: 8b 05 80 1d d1 10 48 89 44 24 28 0f 1f 44 00 00 65 8b 05 83 1d d1 10 83 f8 08 0f 83 9a 02 00 00 89 c0 48 0f a3 05 ac 9a df 0d <73> 16 e8 d5 ec 08 00 84 c0 75 0d f6 05 37 a6 c9 0d 01 0f 84 ad 02
RSP: 0018:ffffc9000a3af4d0 EFLAGS: 00000297
RAX: 0000000000000001 RBX: ffffc9000a3af601 RCX: 0ea79fe99985dd00
RDX: ffffffff900f1201 RSI: ffffffff81738c45 RDI: ffffffff8df3d6a0
RBP: dffffc0000000000 R08: ffffc9000a3af667 R09: 0000000000000000
R10: ffffc9000a3af658 R11: fffff52001475ecd R12: ffffc9000a3afee0
R13: ffffffff81738c45 R14: ffffffff8df3d6a0 R15: ffffffff81738c45
FS:  00007f235cde16c0(0000) GS:ffff8882a9f38000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200001000000 CR3: 000000000dd38000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 unwind_next_frame+0x19a9/0x2390
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 save_stack+0xf5/0x1f0
 __reset_page_owner+0x71/0x1f0
 __free_frozen_pages+0xbc4/0xd30
 vfree+0x25a/0x400
 kcov_close+0x28/0x50
 __fput+0x44c/0xa70
 task_work_run+0x1d4/0x260
 do_exit+0x6b5/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1285/0x1340
 arch_do_signal_or_restart+0xa0/0x790
 exit_to_user_mode_loop+0x72/0x130
 do_syscall_64+0x2bd/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f235bf8f6c9
Code: Unable to access opcode bytes at 0x7f235bf8f69f.
RSP: 002b:00007f235cde1038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: 000000000003fea9 RBX: 00007f235c1e5fa0 RCX: 00007f235bf8f6c9
RDX: 000000000400023c RSI: 00002000000055c0 RDI: 0000000000000006
RBP: 00007f235c011f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000300 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f235c1e6038 R14: 00007f235c1e5fa0 R15: 00007fff792e8d88
 </TASK>
