INFO: task syz.0.2135:17116 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.2135      state:D stack:24648 pid:17116 tgid:17115 ppid:16268  task_flags:0x400140 flags:0x00080002
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/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa7fa98f7c9
RSP: 002b:00007fa7fb8c1038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fa7fabe5fa0 RCX: 00007fa7fa98f7c9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fa7fabe5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa7fabe6038 R14: 00007fa7fabe5fa0 R15: 00007ffe300879e8
 </TASK>
INFO: task syz.9.2149:17174 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.9.2149      state:D stack:25032 pid:17174 tgid:17173 ppid:13523  task_flags:0x400040 flags:0x00080002
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/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4401b8f7c9
RSP: 002b:00007f4402a28038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f4401de5fa0 RCX: 00007f4401b8f7c9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f4401de5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4401de6038 R14: 00007f4401de5fa0 R15: 00007ffcedabaec8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/35:
 #0: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
5 locks held by kworker/1:2/794:
 #0: ffff888168044d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc900052b7ba0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff88810bc08198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a20
 #3: ffff8881b9595198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400
 #4: ffff8881b9752160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400
2 locks held by getty/5637:
 #0: ffff8881735630a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000357b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
4 locks held by udevd/11998:
 #0: ffff8881179922f0 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xb7/0xe20
 #1: ffff888113311488 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x5c/0x420
 #2: ffff888111bd8b48 (kn->active#31){++++}-{0:0}, at: kernfs_seq_start+0xb2/0x420
 #3: ffff8881b9595198 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0
4 locks held by syz-executor/13750:
1 lock held by syz.0.2135/17116:
 #0: ffff888118ecc0e0 (&type->s_umount_key#72){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.9.2149/17174:
 #0: ffff888118ecc0e0 (&type->s_umount_key#72){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.4.2349/18229:
 #0: ffff888118ecc0e0 (&type->s_umount_key#72){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
3 locks held by syz.7.2789/20405:
 #0: ffffffff8f7d2c30 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250
 #1: ffffffff8f2cc708 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8e9/0x1c80
 #2: ffffffff8df43138 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 35 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+0xf60/0xfa0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 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: 13750 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:__lock_acquire+0x73f/0xd20
Code: fb 31 0f 83 e0 05 00 00 48 8d 04 9b 45 8b 66 20 48 8b 4c 24 10 8b 44 c1 f8 44 31 e0 25 00 60 00 00 31 c9 89 c2 f7 da 48 19 c9 <49> 09 cf 85 c0 b8 01 00 00 00 0f 45 e8 eb 4b 48 89 fb 4c 89 f6 a9
RSP: 0018:ffffc9000ad5f780 EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000002 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff88816ca70b80 RDI: ffff88816ca70000
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8410c90a
R10: dffffc0000000000 R11: ffffed1022bd4a1c R12: 0000000000040bf5
R13: 0000000000000003 R14: ffff88816ca70b80 R15: 269750c51413998e
FS:  00005555923cb500(0000) GS:ffff8882a9f36000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4eea898ff0 CR3: 00000001ae968000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 lock_acquire+0x120/0x360
 _raw_spin_lock+0x2e/0x40
 f2fs_write_checkpoint+0xa9a/0x2440
 kill_f2fs_super+0x2cc/0x6d0
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x425/0x4c0
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xe9/0x130
 do_syscall_64+0x2bd/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1e26190af7
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffefd22a138 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f1e261ee72f RCX: 00007f1e26190af7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffefd22a1f0
RBP: 00007ffefd22a1f0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffefd22b280
R13: 00007f1e261ee72f R14: 000000000006243a R15: 00007ffefd22b2c0
 </TASK>
