INFO: task kworker/u8:2:5716 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:2    state:D stack:22840 pid:5716  tgid:5716  ppid:2      task_flags:0x4208060 flags:0x00004000
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+0x4c5/0x800
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
INFO: task syz.2.2858:16329 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.2858      state:D stack:23608 pid:16329 tgid:16328 ppid:5850   task_flags:0x400140 flags:0x00004004
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/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f790b98ebe9
RSP: 002b:00007f790c804038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f790bbc5fa0 RCX: 00007f790b98ebe9
RDX: 0000000000000000 RSI: 00002000000002c0 RDI: 0000000000000006
RBP: 00007f790ba11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f790bbc6038 R14: 00007f790bbc5fa0 R15: 00007ffcb729d928
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_exp_gp_kthr/18:
 #0: ffff88804b039f98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140
1 lock held by khungtaskd/34:
 #0: ffffffff8e139ee0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5674:
 #0: ffff8880298c70a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900027d82f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
4 locks held by kworker/u8:2/5716:
 #0: ffff88801b2f7148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90002f3fbc0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8f52bc30 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf7/0x800
 #3: ffff88811e984700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
5 locks held by kworker/u9:34/8176:
 #0: ffff88804b039f98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140
 #1: ffff88804b024008 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880
 #2: ffff88804b025918 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x1ae/0xf30
 #3: ffffffff99d072c8 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0xbb/0x420
 #4: ffffffff8e139ee0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xa5/0x2390
2 locks held by syz.2.2858/16329:
 #0: ffffffff99e6a8d8 (&rdma_nl_types[idx].sem){.+.+}-{4:4}, at: rdma_nl_rcv+0x302/0x980
 #1: ffff88811e984700 (&device->unregistration_lock){+.+.}-{4:4}, at: __ib_unregister_device+0x284/0x3f0
2 locks held by syz.0.3499/18463:
 #0: ffffffff8f52bc30 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffff88811e984700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.1.4125/20669:
 #0: ffffffff8f52bc30 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffff88811e984700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.4.4178/20855:
 #0: ffffffff8f52bc30 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffff88811e984700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.5.4362/21557:
 #0: ffffffff8f52bc30 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffff88811e984700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.6.4365/21570:
 #0: ffffffff8f52bc30 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffff88811e984700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.3.4543/22236:
 #0: ffffffff8f52bc30 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffff88811e984700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.3.4543/22237:
 #0: ffffffff8f52bc30 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffff88811e984700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
3 locks held by syz-executor/22815:
 #0: ffffffff8f538ac8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8db/0x1c70
 #1: ffff88802ea04d30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: do_setlink+0x388/0x41c0
 #2: ffffffff8e13f978 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730
3 locks held by syz.7.4718/22834:
 #0: ffff88813018a608 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: sock_close+0x9b/0x240
 #1: ffff88811c97d258 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pptp_release+0x52/0x2f0
 #2: ffffffff8e13f978 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730

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

NMI backtrace for cpu 1
CPU: 1 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+0xf93/0xfe0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 22815 Comm: syz-executor 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:io_serial_out+0x7c/0xc0
Code: 72 70 fc 44 89 f9 d3 e5 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 7c e0 d3 fc 41 03 2e 89 d8 89 ea ee <5b> 41 5c 41 5e 41 5f 5d e9 d7 71 2d 06 cc 44 89 f9 80 e1 07 38 c1
RSP: 0018:ffffc90002a5e470 EFLAGS: 00000002
RAX: 0000000000000037 RBX: 0000000000000037 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000000003f8 R08: ffff888106a50237 R09: 1ffff11020d4a046
R10: dffffc0000000000 R11: ffffffff854f38c0 R12: dffffc0000000000
R13: ffffffff99afd8c6 R14: ffffffff99df2420 R15: 0000000000000000
FS:  000055555cbc6500(0000) GS:ffff8880b8618000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f21566f35c0 CR3: 00000000328f4000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 serial8250_console_write+0x1410/0x1ba0
 console_flush_all+0x728/0xc40
 console_unlock+0xc4/0x270
 vprintk_emit+0x5b7/0x7a0
 dev_vprintk_emit+0x337/0x3f0
 dev_printk_emit+0xe0/0x130
 __netdev_printk+0x3d7/0x4d0
 netdev_info+0x10a/0x160
 netif_change_name+0x88c/0x960
 do_setlink+0x9f6/0x41c0
 rtnl_newlink+0x160b/0x1c70
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2155990a7c
Code: 2a 5f 02 00 44 8b 4c 24 2c 4c 8b 44 24 20 89 c5 44 8b 54 24 28 48 8b 54 24 18 b8 2c 00 00 00 48 8b 74 24 10 8b 7c 24 08 0f 05 <48> 3d 00 f0 ff ff 77 34 89 ef 48 89 44 24 08 e8 70 5f 02 00 48 8b
RSP: 002b:00007ffe1222b850 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f21566f35c0 RCX: 00007f2155990a7c
RDX: 0000000000000030 RSI: 00007f21566f3610 RDI: 0000000000000006
RBP: 0000000000000000 R08: 00007ffe1222b8a4 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000006
R13: 0000000000000000 R14: 00007f21566f3610 R15: 0000000000000000
 </TASK>
