INFO: task syz.3.1938:10431 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.3.1938      state:D stack:28144 pid:10431 tgid:10430 ppid:7179   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7bf/0x1550
 nfsd_shutdown_threads+0x4e/0xd0
 nfsd_umount+0x41/0x60
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x3d3/0x460
 task_work_run+0x1d9/0x270
 exit_to_user_mode_loop+0x1fa/0x730
 do_syscall_64+0x353/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6d1879de99
RSP: 002b:00007f6d1971f028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: fffffffffffffffe RBX: 00007f6d18a25fa0 RCX: 00007f6d1879de99
RDX: 0000200000000040 RSI: 0000200000000000 RDI: 0000000000000000
RBP: 00007f6d18833eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6d18a26038 R14: 00007f6d18a25fa0 R15: 00007fff40163128
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/35:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by udevd/5058:
2 locks held by getty/5439:
 #0: ffff8881697490a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034732e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
2 locks held by syz-executor/5595:
 #0: ffff88812103b160 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2d/0x160
 #1: ffff888121024440 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x57/0x7d0
3 locks held by syz.0.1790/10111:
 #0: ffff88817109a4f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff888170ea4450 (sb_writers#38){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffffffff8ee8e620 (nfsd_mutex){+.+.}-{4:4}, at: write_threads+0x39d/0x5a0
2 locks held by syz.3.1938/10431:
 #0: ffff8881165040d8 (&type->s_umount_key#112){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
 #1: ffffffff8ee8e620 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0
1 lock held by syz.1.2094/10978:
 #0: ffff8881165040d8 (&type->s_umount_key#112){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz.1.2094/10979:
 #0: ffff8881165040d8 (&type->s_umount_key#112){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz.1.2094/10980:
 #0: ffff8881165040d8 (&type->s_umount_key#112){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz-executor/13563:
 #0: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 35 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+0x17a/0x380
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 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: 13563 Comm: syz-executor 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
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70
Code: 8b 3d d4 ae 88 0c 48 89 de 5b e9 b3 08 62 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d 78 ee a5 11 65 8b 15 99 ee a5 11 81 e2 00 01 ff 00 74
RSP: 0018:ffffc90007d6fbb8 EFLAGS: 00000a02
RAX: ffffffff824af335 RBX: ffff8881bcefc900 RCX: 0000000000000000
RDX: ffffc90007d6fe00 RSI: ffff8881bcefc900 RDI: 00000000ffffff9c
RBP: ffffc90007d6fdb0 R08: ffff888172bfc4c3 R09: 1ffff1102e57f898
R10: dffffc0000000000 R11: ffffed102e57f899 R12: 1ffff92000fadf80
R13: dffffc0000000000 R14: f8f8f8f8f8f8f8f8 R15: ffffc90007d6fe00
FS:  000055557d67a500(0000) GS:ffff88818d951000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055557d69da68 CR3: 000000019f81e000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 do_file_open+0xa5/0x4a0
 do_sys_openat2+0x115/0x200
 __x64_sys_openat+0x138/0x170
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa257d5e6ce
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007ffe8aaa0998 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000055557d67a500 RCX: 00007fa257d5e6ce
RDX: 0000000000000002 RSI: 00007ffe8aaa0ae0 RDI: ffffffffffffff9c
RBP: 00007ffe8aaa0a8c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000000d4
R13: 00000000000927c0 R14: 000000000005900f R15: 00007ffe8aaa0ae0
 </TASK>
