INFO: task syz-executor:21511 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:21832 pid:21511 tgid:21511 ppid:1      task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 wb_wait_for_completion+0x15f/0x260
 __writeback_inodes_sb_nr+0x1f6/0x250
 sync_filesystem+0xa3/0x230
 generic_shutdown_super+0x6f/0x2c0
 bch2_kill_sb+0x41/0x50
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x425/0x4c0
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xec/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f26dd18ff57
RSP: 002b:00007fff467e6ce8 EFLAGS: 00000246
 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f26dd211c2d RCX: 00007f26dd18ff57
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff467e6da0
RBP: 00007fff467e6da0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fff467e7e30
R13: 00007f26dd211c2d R14: 00000000000fb086 R15: 00007fff467e7e70
 </TASK>
INFO: task syz.6.3324:22278 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.3324      state:D
 stack:25128 pid:22278 tgid:22277 ppid:16509  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: 0033:0x7f671378ec29
RSP: 002b:00007f67146f9038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f67139d5fa0 RCX: 00007f671378ec29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f67139d5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f67139d6038 R14: 00007f67139d5fa0 R15: 00007ffee0fa45d8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e13a0e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5674:
 #0: ffff888104e910a0 (&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
5 locks held by kworker/0:4/5946:
 #0: ffff888104ba2948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000470fbc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff8881098b4198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a20
 #3: ffff88803bc9f198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400
 #4: ffff888049104160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400
2 locks held by kworker/u10:5/16539:
 #0: ffff8881001a7148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000319fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
1 lock held by syz-executor/21511:
 #0: ffff8881175ac0e0 (&type->s_umount_key#51){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
1 lock held by syz.6.3324/22278:
 #0: ffff8881175ac0e0 (&type->s_umount_key#51){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by udevd/23082:
 #0: ffff888136639f98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140
1 lock held by syz-executor/23265:
 #0: ffffffff8e13fb78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730
1 lock held by syz-executor/23929:

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

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+0x439/0x7d0
 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: 23265 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:io_serial_out+0x7c/0xc0
Code: ff 6f fc 44 89 f9 d3 e5 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 4c 7d d3 fc 41 03 2e 89 d8 89 ea ee <5b> 41 5c 41 5e 41 5f 5d c3 cc cc cc cc cc 44 89 f9 80 e1 07 38 c1
RSP: 0018:ffffc90002e9f470 EFLAGS: 00000006
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 00000000000003f9 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000000003f9 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff854fad60 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff99df7460 R15: 0000000000000000
FS:  000055559011e500(0000) GS:ffff8881a3c13000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe3f966f88 CR3: 000000012bed6000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 serial8250_console_write+0x5f2/0x1ba0
 console_flush_all+0x728/0xc40
 console_unlock+0xc4/0x270
 vprintk_emit+0x5b7/0x7a0
 __bch2_print+0x176/0x220
 bch2_fs_read_only+0x188/0xb00
 __bch2_fs_stop+0x100/0x900
 generic_shutdown_super+0x135/0x2c0
 bch2_kill_sb+0x41/0x50
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x425/0x4c0
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xec/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9cd4b8ff57
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:00007ffe3f967738 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f9cd4c11c2d RCX: 00007f9cd4b8ff57
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe3f9677f0
RBP: 00007ffe3f9677f0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffe3f968880
R13: 00007f9cd4c11c2d R14: 00000000001213b5 R15: 00007ffe3f9688c0
 </TASK>
