INFO: task kworker/u8:0:12 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:0    state:D stack:23792 pid:12    tgid:12    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.2.4656:22050 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.4656      state:D stack:24648 pid:22050 tgid:22049 ppid:5848   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: 0033:0x7fbdb538ebe9
RSP: 002b:00007fbdb627a038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fbdb55b5fa0 RCX: 00007fbdb538ebe9
RDX: 0000000000000000 RSI: 00002000000002c0 RDI: 0000000000000005
RBP: 00007fbdb5411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbdb55b6038 R14: 00007fbdb55b5fa0 R15: 00007ffd5e69a2f8
 </TASK>
INFO: lockdep is turned off.
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+0xf93/0xfe0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 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: 27936 Comm: syz.3.6255 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:debug_check_no_obj_freed+0x23e/0x470
Code: 44 24 18 4d 8d 67 18 4c 89 e0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 e7 e8 d6 d5 52 fd 49 8b 2c 24 <48> 3b 6c 24 50 0f 92 c0 49 39 ed 0f 96 c1 08 c1 75 8c 4d 8d 67 10
RSP: 0018:ffffc9000482f818 EFLAGS: 00000046
RAX: 1ffff1100433b35a RBX: 0000000000000002 RCX: dffffc0000000000
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc9000482f700
RBP: ffff8881062bc260 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000905ee0 R12: ffff8880219d9ad0
R13: ffffc9003fcfc000 R14: 1ffff1100433b357 R15: ffff8880219d9ab8
FS:  00007f72dba576c0(0000) GS:ffff8881a3c1a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000940000 CR3: 000000000df36000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 remove_vm_area+0x1d3/0x300
 vfree+0x63/0x400
 kcov_close+0x28/0x50
 __fput+0x44c/0xa70
 task_work_run+0x1d4/0x260
 do_exit+0x6b5/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 exit_to_user_mode_loop+0x75/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f72dab8ebe9
Code: Unable to access opcode bytes at 0x7f72dab8ebbf.
RSP: 002b:00007f72dba57038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: 0000000000940a70 RBX: 00007f72dadb6180 RCX: 00007f72dab8ebe9
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 000000000000000d
RBP: 00007f72dac11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f72dadb6218 R14: 00007f72dadb6180 R15: 00007fff7f8e5bf8
 </TASK>
