INFO: task kworker/u8:5:9443 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:22544 pid:9443  tgid:9443  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.1.2842:16501 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.2842      state:D stack:25400 pid:16501 tgid:16500 ppid:5836   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: 0033:0x7fd68a18ebe9
RSP: 002b:00007fd6883f6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fd68a3b5fa0 RCX: 00007fd68a18ebe9
RDX: 0000000000000000 RSI: 00002000000002c0 RDI: 0000000000000003
RBP: 00007fd68a211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd68a3b6038 R14: 00007fd68a3b5fa0 R15: 00007fff9fb70b28
 </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: 5664 Comm: sshd 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:unwind_get_return_address+0x63/0x90
Code: 37 00 74 08 48 89 df e8 1b 57 b0 00 48 8b 3b e8 33 bf 19 00 85 c0 74 14 43 80 3c 37 00 74 08 48 89 df e8 00 57 b0 00 48 8b 03 <eb> 02 31 c0 5b 41 5e 41 5f e9 0f fb 09 0a cc 89 d9 80 e1 07 80 c1
RSP: 0018:ffffc90001c2f2c8 EFLAGS: 00000046
RAX: ffffffff81847ad8 RBX: ffffc90001c2f330 RCX: cdf7c9d91580e900
RDX: ffffc90001c2f301 RSI: ffffffff8be33660 RDI: ffffffff81847ad8
RBP: ffffc90001c2f370 R08: ffffc90001c2fbc8 R09: 0000000000000000
R10: ffffc90001c2f338 R11: fffff52000385e69 R12: ffff88802142b980
R13: 1ffff92000385ee0 R14: dffffc0000000000 R15: 1ffff92000385e66
FS:  00007ff3c1ee2800(0000) GS:ffff8881a3c1a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f852320a198 CR3: 00000001105c2000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 arch_stack_walk+0xfc/0x150
 stack_trace_save+0x9c/0xe0
 kasan_save_stack+0x3e/0x60
 kasan_record_aux_stack+0xbd/0xd0
 call_rcu+0x157/0x9c0
 kmem_cache_free+0x309/0x400
 release_task+0x1105/0x17f0
 wait_consider_task+0x1944/0x2e10
 __do_wait+0x153/0x740
 do_wait+0x1f8/0x520
 kernel_wait4+0x1af/0x280
 __x64_sys_wait4+0x133/0x1e0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff3c1afc476
Code: 10 00 00 00 48 89 d1 89 f2 48 89 fe 83 cf ff e9 00 00 00 00 49 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 20 b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 73 48 8b 15 83 49 0f 00 f7 d8 64 89 02 48 83
RSP: 002b:00007fff75bb52c8 EFLAGS: 00000246 ORIG_RAX: 000000000000003d
RAX: ffffffffffffffda RBX: 00007ff3c1ee2698 RCX: 00007ff3c1afc476
RDX: 0000000000000001 RSI: 00007fff75bb52d4 RDI: 00000000ffffffff
RBP: 0000000000000004 R08: 0000000000000008 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff75bb52d4
R13: 00007fff75bb58f8 R14: 0000000000000002 R15: 000055a2730d626c
 </TASK>
