INFO: task syz.3.462:7498 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.3.462       state:D stack:27432 pid:7498  tgid:7496  ppid:6641   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d4/0x5630
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 write_threads+0x39d/0x5a0
 nfsctl_transaction_write+0x10f/0x160
 vfs_write+0x296/0xba0
 ksys_write+0x150/0x270
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f860e59e159
RSP: 002b:00007f860f528028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f860e826090 RCX: 00007f860e59e159
RDX: 0000000000000002 RSI: 0000200000000280 RDI: 0000000000000005
RBP: 00007f860e63506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f860e826128 R14: 00007f860e826090 R15: 00007ffda1f43ba8
 </TASK>

Showing all locks held in the system:
locks held by khungtaskd/35: 1, last CPU#0:
 #0: ffffffff8eb5a0e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by getty/5418: 2, on CPU#0:
 #0: ffff88810fc020a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034832e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
locks held by syz-executor/6643: 2, on CPU#0:
 #0: ffff8881aeb6c0e8 (&type->s_umount_key#72){+.+.}-{4:4}, at: deactivate_super+0xac/0xe0
 #1: ffffffff8ee8fbe0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0
locks held by syz-executor/6644: 2, on CPU#0:
 #0: ffff88801b68a0e8 (&type->s_umount_key#72){+.+.}-{4:4}, at: deactivate_super+0xac/0xe0
 #1: ffffffff8ee8fbe0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0
locks held by syz.3.462/7497: 3, on CPU#0:
 #0: ffff8881063d76f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff88801bfae460 (sb_writers#19){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffffffff8ee8fbe0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10
locks held by syz.3.462/7498: 3, on CPU#1:
 #0: ffff888176bb40f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff88801bfae460 (sb_writers#19){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffffffff8ee8fbe0 (nfsd_mutex){+.+.}-{4:4}, at: write_threads+0x39d/0x5a0
locks held by syz-executor/8069: 2, on CPU#0:
 #0: ffff88816a0220e8 (&type->s_umount_key#72){+.+.}-{4:4}, at: deactivate_super+0xac/0xe0
 #1: ffffffff8ee8fbe0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0
locks held by syz-executor/8127: 2, on CPU#0:
 #0: ffff8881027080e8 (&type->s_umount_key#72){+.+.}-{4:4}, at: deactivate_super+0xac/0xe0
 #1: ffffffff8ee8fbe0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0
locks held by syz-executor/8255: 2, on CPU#0:
 #0: ffff88816f8000e8 (&type->s_umount_key#72){+.+.}-{4:4}, at: deactivate_super+0xac/0xe0
 #1: ffffffff8ee8fbe0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0
locks held by syz.1.692/8634: 1, on CPU#0:
 #0: ffff888175f53070 (&hiddev->existancelock){+.+.}-{4:4}, at: hiddev_ioctl+0x181/0x16f0
locks held by syz.1.692/8691: 1, on CPU#1:
 #0: ffff888175f53070 (&hiddev->existancelock){+.+.}-{4:4}, at: hiddev_ioctl+0x181/0x16f0
locks held by syz.2.699/8725: 2, on CPU#0:
 #0: ffffffff8f8e2ee8 (minor_rwsem#2){++++}-{4:4}, at: usb_open+0x30/0x1e0
 #1: ffff888175f53070 (&hiddev->existancelock){+.+.}-{4:4}, at: hiddev_open+0xa4/0x560

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

NMI backtrace for cpu 0
CPU: 0 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+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: 8730 Comm: syz.7.701 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:__lock_acquire+0x6a9/0x2cf0
Code: 8d 44 00 00 31 ed 85 c0 0f 84 19 0d 00 00 83 3d 0c 04 d5 18 00 75 13 48 63 44 24 20 48 0f a3 05 1d 74 d1 12 0f 83 62 1e 00 00 <49> 8b 9e 98 0b 00 00 48 83 3c 24 00 75 1e 48 83 fb ff 0f 94 c0 83
RSP: 0018:ffffc900043d7338 EFLAGS: 00000047
RAX: 0000000000000007 RBX: 0000000000000000 RCX: ffffffff94151a88
RDX: 0000000000000008 RSI: ffff888036e865a8 RDI: ffff888036e85a00
RBP: 0000000000000000 R08: ffffffff8177710f R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb5a0e0 R12: ffffffffffffff05
R13: ffff888036e865a8 R14: ffff888036e85a00 R15: ffff888036e865a8
FS:  00007f894b2556c0(0000) GS:ffff8882a8f39000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c342a39 CR3: 0000000111476000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 lock_acquire+0x106/0x350
 unwind_next_frame+0xac/0x2550
 arch_stack_walk+0x11b/0x150
 stack_trace_save+0xa9/0x100
 save_stack+0x122/0x230
 __reset_page_owner+0x71/0x1f0
 free_pages_prepare+0x960/0xa60
 __free_contig_range_common+0x174/0x340
 free_pages_bulk+0x48/0x120
 vfree+0x226/0x4a0
 kcov_close+0x28/0x50
 __fput+0x418/0xa50
 task_work_run+0x1d9/0x270
 do_exit+0x73a/0x2360
 do_group_exit+0x22d/0x2f0
 get_signal+0x121b/0x12c0
 arch_do_signal_or_restart+0xbb/0x860
 exit_to_user_mode_loop+0x10e/0x770
 do_syscall_64+0x328/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f894a39ddeb
Code: Unable to access opcode bytes at 0x7f894a39ddc1.
RSP: 002b:00007f894b252f00 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 00007f894a39ddeb
RDX: 00007f894b253fd0 RSI: 0000000080085502 RDI: 0000000000000003
RBP: 00007f894b253fd0 R08: 0000000000000000 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000080085502
R13: 0000000800000000 R14: 0000000000000005 R15: 00007f894a4539b6
 </TASK>
