INFO: task syz.4.2529:14820 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.2529      state:D stack:24008 pid:14820 tgid:14819 ppid:8029   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1350
 nfsd_nl_threads_get_doit+0x1b6/0x6f0
 genl_family_rcv_msg_doit+0x215/0x300
 genl_rcv_msg+0x60e/0x790
 netlink_rcv_skb+0x208/0x470
 genl_rcv+0x28/0x40
 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: 0033:0x7fd6be98eba9
RSP: 002b:00007fd6bf8da038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fd6bebd5fa0 RCX: 00007fd6be98eba9
RDX: 0000000000008000 RSI: 0000200000006e40 RDI: 0000000000000009
RBP: 00007fd6bea11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd6bebd6038 R14: 00007fd6bebd5fa0 R15: 00007ffed04972e8
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/0:0/9:
 #0: ffff88801bfeb548 ((wq_completion)infiniband){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc900000c7bc0 ((work_completion)(&work->work)#2){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff888110129290 (&rxe->usdev_lock){+.+.}-{4:4}, at: rxe_query_port+0x7e/0x3b0
 #3: ffffffff8f53a288 (rtnl_mutex){+.+.}-{4:4}, at: ib_get_eth_speed+0x151/0x7b0
1 lock held by khungtaskd/34:
 #0: ffffffff8e13a120 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5676:
 #0: ffff88802067f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900029062f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
1 lock held by syz-executor/5800:
2 locks held by syz.1.1776/12186:
 #0: ffffffff8f59f9b0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e418c88 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
3 locks held by kworker/u10:49/14372:
 #0: ffff88801a489148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc900035d7bc0 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8f53a288 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60
2 locks held by syz.4.2529/14820:
 #0: ffffffff8f59f9b0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e418c88 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_get_doit+0x1b6/0x6f0
2 locks held by syz-executor/16085:
3 locks held by syz-executor/16098:
5 locks held by kworker/u8:5/16116:
 #0: ffff88801b2f7148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90002f4fbc0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8f52d3d0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf7/0x800
 #3: ffffffff8f53a288 (rtnl_mutex){+.+.}-{4:4}, at: default_device_exit_batch+0xdc/0x890
 #4: ffffffff8e13fbb8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730
2 locks held by syz.4.2917/16353:
 #0: ffffffff8f59f9b0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8e418c88 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690
7 locks held by syz-executor/16693:
 #0: ffff888106c8c428 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x211/0xb30
 #1: ffff8881119cdc88 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1e0/0x4f0
 #2: ffff888021640d28 (kn->active#48){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x203/0x4f0
 #3: ffffffff8edb0588 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd1/0x360
 #4: ffff888128ac30e8 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb6/0x800
 #5: ffff888128ac1250 (&devlink->lock_key#9){+.+.}-{4:4}, at: nsim_drv_remove+0x50/0x160
 #6: ffffffff8f53a288 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_dev_lock+0x257/0x2f0
1 lock held by syz.7.3054/16805:
 #0: ffffffff8f53a288 (rtnl_mutex){+.+.}-{4:4}, at: dev_ioctl+0x7a4/0x1150
1 lock held by syz.1.3061/16831:
 #0: ffffffff8e13fbb8 (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+0xf93/0xfe0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 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: 16831 Comm: syz.1.3061 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:rcu_is_watching+0x5e/0xb0
Code: 03 42 80 3c 38 00 74 08 4c 89 f7 e8 ac d0 7c 00 48 c7 c3 98 ff a1 92 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 84 c0 75 34 <8b> 03 65 ff 0d d9 5d fa 10 74 11 83 e0 04 c1 e8 02 5b 41 5e 41 5f
RSP: 0018:ffffc90006227478 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888136632f98 RCX: aff34a297aa21900
RDX: 0000000000000000 RSI: ffffffff8be33e60 RDI: ffffffff8be33e20
RBP: ffffffff8172d195 R08: 0000000000000000 R09: 0000000000000000
R10: ffffc90006227658 R11: ffffffff81ac4d00 R12: 0000000000000002
R13: ffffffff8e13a120 R14: ffffffff8dbe2d18 R15: dffffc0000000000
FS:  000055555deab500(0000) GS:ffff8881a3c13000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9e1de87e20 CR3: 000000000df36000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 lock_acquire+0x5f/0x360
 unwind_next_frame+0xc2/0x2390
 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+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: 0033:0x7f3c84bc1465
Code: Unable to access opcode bytes at 0x7f3c84bc143b.
RSP: 002b:00007ffee2e62560 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007f3c84dd5fa0 RCX: 00007f3c84bc1465
RDX: 00007ffee2e625a0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f3c84dd7da0 R08: 0000000000000000 R09: 7fffffffffffffff
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000094f35
R13: 00007f3c84dd6090 R14: ffffffffffffffff R15: 00007ffee2e626e0
 </TASK>
