INFO: task kworker/u8:4:5890 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:4    state:D stack:23720 pid:5890  tgid:5890  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+0x4d8/0x810
 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.0.1481:12523 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1481      state:D stack:22808 pid:12523 tgid:12517 ppid:5847   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/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc0d218eba9
RSP: 002b:00007fc0d03f6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fc0d23d6090 RCX: 00007fc0d218eba9
RDX: 0000000000000000 RSI: 00002000000002c0 RDI: 0000000000000008
RBP: 00007fc0d2211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc0d23d6128 R14: 00007fc0d23d6090 R15: 00007fff0cdadc88
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e33d660 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5671:
 #0: ffff88810fcb00a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000290e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
4 locks held by kworker/u8:4/5890:
 #0: ffff88801b6ff148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc900039f7ba0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8f738410 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf7/0x810
 #3: ffff88801f4e0700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
4 locks held by kworker/0:3/5892:
3 locks held by kworker/1:6/5905:
 #0: ffff88801a875548 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90003a97ba0 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8e3430f8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730
2 locks held by syz.0.1481/12523:
 #0: ffffffff9a0a2bb8 (&rdma_nl_types[idx].sem){.+.+}-{4:4}, at: rdma_nl_rcv+0x302/0x980
 #1: ffff88801f4e0700 (&device->unregistration_lock){+.+.}-{4:4}, at: __ib_unregister_device+0x284/0x3f0
2 locks held by syz.3.1708/13682:
 #0: ffffffff8f738410 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffff88801f4e0700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.3.1708/13685:
 #0: ffffffff8f738410 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffff88801f4e0700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
2 locks held by syz.1.2060/15310:
 #0: ffffffff9a0a2bb8 (&rdma_nl_types[idx].sem){.+.+}-{4:4}, at: rdma_nl_rcv+0x302/0x980
 #1: ffff88801f4e0700 (&device->unregistration_lock){+.+.}-{4:4}, at: __ib_unregister_device+0x284/0x3f0
2 locks held by syz.2.2094/15475:
 #0: ffffffff9a0a2bb8 (&rdma_nl_types[idx].sem){.+.+}-{4:4}, at: rdma_nl_rcv+0x302/0x980
 #1: ffff88801f4e0700 (&device->unregistration_lock){+.+.}-{4:4}, at: __ib_unregister_device+0x284/0x3f0
2 locks held by syz.4.2149/15783:
 #0: ffffffff8f738410 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffff88801f4e0700 (&device->unregistration_lock){+.+.}-{4:4}, at: rdma_dev_change_netns+0x39/0x300
3 locks held by syz-executor/16263:
 #0: ffffffff8f738410 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0
 #1: ffffffff8f7452c8 (rtnl_mutex){+.+.}-{4:4}, at: ops_undo_list+0x2a4/0x990
 #2: ffffffff8e3430f8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730

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

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+0xf60/0xfa0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 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: 5291 Comm: udevd 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+0x103/0x3e0
Code: 8b 87 28 0b 00 00 85 c0 0f 84 1d 01 00 00 4c 89 6c 24 18 48 89 5c 24 08 44 8d 60 ff 49 8d af 30 0b 00 00 4d 63 ec 48 89 04 24 <83> f8 32 0f 83 44 02 00 00 4a 8d 1c ad 00 00 00 00 4c 01 eb 48 8d
RSP: 0018:ffffc90002616dd0 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000206 RCX: 1aade42e020fc600
RDX: ffffc90002616f01 RSI: ffffffff8dbd5c61 RDI: ffffffff8c038200
RBP: ffff888107d1c530 R08: ffffc90002616ff0 R09: 0000000000000000
R10: ffffc90002616fb8 R11: fffff520004c2df9 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff8e33d660 R15: ffff888107d1ba00
FS:  00007f2a4e292c80(0000) GS:ffff8880b83e0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005639d74ee5c8 CR3: 0000000028882000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 unwind_next_frame+0x19a9/0x2390
 __unwind_start+0x5b9/0x760
 arch_stack_walk+0xe4/0x150
 stack_trace_save+0x9c/0xe0
 kasan_save_stack+0x3e/0x60
 kasan_record_aux_stack+0xbd/0xd0
 call_rcu+0x157/0x9c0
 __destroy_inode+0x2da/0x670
 evict+0x797/0x9c0
 __dentry_kill+0x209/0x660
 shrink_kill+0xa9/0x2c0
 shrink_dentry_list+0x2e0/0x5e0
 shrink_dcache_parent+0xa1/0x2c0
 d_invalidate+0x11b/0x260
 lookup_fast+0x3c3/0x5b0
 link_path_walk+0x642/0xea0
 path_openat+0x28c/0x3830
 do_filp_open+0x1fa/0x410
 do_sys_openat2+0x121/0x1c0
 __x64_sys_openat+0x138/0x170
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2a4df169a4
Code: 24 20 48 8d 44 24 30 48 89 44 24 28 64 8b 04 25 18 00 00 00 85 c0 75 2c 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 76 60 48 8b 15 55 a4 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffc30774580 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 00007f2a4df169a4
RDX: 0000000000080000 RSI: 00007ffc307746b8 RDI: 00000000ffffff9c
RBP: 00007ffc307746b8 R08: 0000000000000008 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000080000
R13: 000056072e8ffb42 R14: 0000000000000001 R15: 0000000000000000
 </TASK>
