INFO: task syz.4.2263:24982 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.2263      state:D stack:24840 pid:24982 tgid:24980 ppid:23002  task_flags:0x400140 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
 __se_sys_quotactl+0x353/0x950
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2341f8eba9
RSP: 002b:00007f2342d6e038 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007f23421d5fa0 RCX: 00007f2341f8eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff80000101
RBP: 00007f2342011e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f23421d6038 R14: 00007f23421d5fa0 R15: 00007ffd6ccd9f28
 </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
7 locks held by kworker/u10:2/40:
2 locks held by getty/5676:
 #0: ffff888106e270a0 (&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
2 locks held by syz-executor/21641:
1 lock held by syz.4.2263/24982:
 #0: ffff88801fe9c0e0 (&type->s_umount_key#56){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.0.2375/25903:
 #0: ffff88801fe9c0e0 (&type->s_umount_key#56){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz-executor/26184:
 #0: ffffffff8e13f9b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730
1 lock held by syz.9.2433/26353:
 #0: ffff88801fe9c0e0 (&type->s_umount_key#56){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.4.2692/28391:
2 locks held by syz.5.2693/28403:

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

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: 7194 Comm: kworker/u8:5 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
Workqueue: bat_events batadv_nc_worker
RIP: 0010:rcu_is_watching+0x70/0xb0
Code: c3 98 df 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 4f fa 10 74 11 83 e0 04 c1 e8 02 5b <41> 5e 41 5f c3 cc cc cc cc cc e8 c1 66 8d ff eb e8 48 c7 c7 00 fc
RSP: 0018:ffffc90004e3f8f0 EFLAGS: 00000202
RAX: 0000000000000001 RBX: ffff88802963da00 RCX: 6104c2b9170c8100
RDX: 0000000000000000 RSI: ffffffff8be33960 RDI: ffffffff8be33920
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520009c7f20 R12: ffff8880465b8b40
R13: ffffffff8b481908 R14: ffffffff8dbe1d18 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8881a3c15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdcbae6d000 CR3: 0000000021296000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 lock_release+0x4b/0x3e0
 _raw_spin_unlock_bh+0x1b/0x40
 batadv_nc_purge_paths+0x318/0x3b0
 batadv_nc_worker+0x328/0x610
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
