INFO: task syz.6.8197:31076 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.8197      state:D stack:28328 pid:31076 tgid:31075 ppid:30907  task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_read_slowpath+0x5fd/0x8f0
 down_read+0x98/0x2e0
 super_lock+0x2a9/0x3b0
 __iterate_supers+0x126/0x290
 ksys_sync+0x94/0x150
 __ia32_sys_sync+0xe/0x20
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd253b8ebe9
RSP: 002b:00007fd254ad4038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd253dc5fa0 RCX: 00007fd253b8ebe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd253dc5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd253dc6038 R14: 00007fd253dc5fa0 R15: 00007ffea4aed688
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5677:
 #0: ffff88801fa670a0 (&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
3 locks held by kworker/0:4/5898:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000385fbc0 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8f538c48 (rtnl_mutex){+.+.}-{4:4}, at: switchdev_deferred_process_work+0xe/0x20
3 locks held by kworker/u9:17/17660:
 #0: ffff888136639f98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140
 #1: ffff888136624008 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880
 #2: ffffffff8f538c48 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60
2 locks held by syz-executor/25688:
1 lock held by syz.4.6490/25711:
1 lock held by syz.4.7609/29267:
3 locks held by syz.0.7811/29918:
1 lock held by syz.0.8057/30623:
1 lock held by syz.6.8197/31076:
 #0: ffff88812864c0e0 (&type->s_umount_key#66){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.0.8277/31286:
1 lock held by syz.0.8277/31289:
2 locks held by syz.0.9013/1130:
1 lock held by syz.7.9167/1589:
 #0: ffff88812864c0e0 (&type->s_umount_key#66){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz-executor/1863:
 #0: ffffffff8e13f9b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730
1 lock held by syz.0.9257/2034:

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

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+0x3fc/0x770
 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: 1863 Comm: syz-executor 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+0x55/0xb0
Code: fd bd 8d 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 3c bc 7c 00 48 c7 c3 98 af 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 19 20 fa 10 74 11 83 e0
RSP: 0018:ffffc9000496f4b0 EFLAGS: 00000a06
RAX: 1ffff11026cc65f3 RBX: ffff888136632f98 RCX: 85efe15ef7825d00
RDX: ffffc9000496f601 RSI: ffffffff8be33860 RDI: ffffffff8be33820
RBP: dffffc0000000000 R08: ffffc9000496fec0 R09: 0000000000000000
R10: ffffc9000496f658 R11: fffff5200092decd R12: ffffc9000496fed0
R13: ffffffff8172c195 R14: ffffffff8dbdfd18 R15: dffffc0000000000
FS:  000055556be1b500(0000) GS:ffff8881a3c18000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33311ff8 CR3: 000000002a28e000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 lock_release+0x4b/0x3e0
 unwind_next_frame+0x19a9/0x2390
 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: 0033:0x7fa654b90a7c
Code: Unable to access opcode bytes at 0x7fa654b90a52.
RSP: 002b:00007ffd677fc4a0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: 0000000000000068 RBX: 00007fa6558f4620 RCX: 00007fa654b90a7c
RDX: 0000000000000068 RSI: 00007fa6558f4670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffd677fc4f4 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007fa6558f4670 R15: 0000000000000000
 </TASK>
