INFO: task syz.1.1131:8371 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.1131      state:D stack:28056 pid:8371  tgid:8370  ppid:5590   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d4/0x5630
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 nfsd_shutdown_threads+0x4e/0xd0
 nfsd_umount+0x41/0x60
 deactivate_locked_super+0xbc/0x110
 put_fs_context+0x93/0xb00
 fscontext_release+0x62/0x80
 __fput+0x418/0xa50
 fput_close_sync+0x11f/0x240
 __x64_sys_close+0x7e/0x110
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe21239e159
RSP: 002b:00007fe213241028 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007fe212625fa0 RCX: 00007fe21239e159
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007fe21243506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe212626038 R14: 00007fe212625fa0 R15: 00007ffe4f95cdf8
 </TASK>

Showing all locks held in the system:
locks held by khungtaskd/34: 1, last CPU#0:
 #0: ffffffff8eb5a0e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by getty/5419: 2, on CPU#0:
 #0: ffff88810f8750a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034762e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
locks held by syz-executor/5580: 1, last CPU#1:
 #0: ffff88823c63b2e0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2d/0x160
locks held by kworker/0:4/5648: 6, on CPU#0:
 #0: ffff8881681b1140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0xa1a/0x14c0
 #1: ffffc90004f77c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0xa1a/0x14c0
 #2: ffff8881709851d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30
 #3: ffff888170a22568 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x20a1/0x4d30
 #4: ffff888170948760 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x20c9/0x4d30
 #5: ffffffff8f8d8348 (ehci_cf_port_reset_rwsem){.+.+}-{4:4}, at: hub_port_reset+0x14d/0x1810
locks held by syz.2.710/7356: 3, on CPU#0:
 #0: ffff8881775984f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff8881bfdac460 (sb_writers#28){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffffffff8ee8fbe0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10
locks held by syz.1.1131/8371: 2, on CPU#0:
 #0: ffff8881134b80e8 (&type->s_umount_key#121){++++}-{4:4}, at: deactivate_super+0xac/0xe0
 #1: ffffffff8ee8fbe0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0
locks held by syz.0.2073/10922: 1, on CPU#1:
 #0: ffff8881134b80e8 (&type->s_umount_key#121){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
locks held by syz.6.2104/10989: 3, on CPU#0:
 #0: ffff88801bd798f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff88801bee6460 (sb_writers#28){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffffffff8ee8fbe0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 34 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
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+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17d/0x390
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 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: 1129 Comm: kworker/u9:3 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:lockdep_softirqs_on+0x18/0x180
Code: 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 41 57 41 56 53 65 48 8b 1d 87 eb cb 11 83 3d b8 73 b5 0e 00 <0f> 84 11 01 00 00 65 8b 05 23 30 cc 11 85 c0 0f 85 02 01 00 00 83
RSP: 0018:ffffc90006bb7a00 EFLAGS: 00000002
RAX: 0000000000000200 RBX: ffff888102790000 RCX: 8000000000000203
RDX: 0000000000000000 RSI: ffffffff8c4bdd60 RDI: ffffffff874bc7f4
RBP: ffff8881779df800 R08: ffffffff9057c737 R09: 1ffffffff20af8e6
R10: dffffc0000000000 R11: fffffbfff20af8e7 R12: 00000000000000d8
R13: dffffc0000000000 R14: ffffffff874bc7f4 R15: ffff8881bde4a4a8
FS:  0000000000000000(0000) GS:ffff8882a8f39000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2d72503fe0 CR3: 00000001116f0000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __local_bh_enable_ip+0x8e/0x140
 nsim_dev_trap_report_work+0x7a4/0xb40
 process_scheduled_works+0xa88/0x14c0
 worker_thread+0xa47/0xfb0
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
