INFO: task syz-executor:7670 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:17704 pid:7670  tgid:7670  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: 0033:0x7f3f7a18ff17
RSP: 002b:00007ffd8a35cc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f3f7a211c05 RCX: 00007f3f7a18ff17
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd8a35cd30
RBP: 00007ffd8a35cd30 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffd8a35ddc0
R13: 00007f3f7a211c05 R14: 0000000000024e35 R15: 00007ffd8a35de00
 </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 kworker/u10:3/994:
 #0: ffff888102ad6948 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90006b4fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
2 locks held by getty/5677:
 #0: ffff88810d5670a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900028fb2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
3 locks held by syz-executor/6947:
1 lock held by syz-executor/7670:
 #0: ffff8881091740e0 (&type->s_umount_key#63){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
1 lock held by syz.4.507/10657:
 #0: ffff888125ef20e0 (&type->s_umount_key#58){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
5 locks held by syz.5.558/11246:

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

NMI backtrace for cpu 1
CPU: 1 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5281 Comm: syslogd 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:validate_chain+0x2a3/0x2140
Code: 00 e8 31 d6 ff ff 44 39 35 72 a1 0a 14 73 53 e8 33 10 27 03 89 c3 e8 dc 9a ff ff 85 db 0f 85 56 02 00 00 83 3d fd 1a 06 0e 00 <0f> 84 a2 17 00 00 b8 01 00 00 00 65 48 8b 0d aa d9 02 11 48 3b 8c
RSP: 0018:ffffc90002637270 EFLAGS: 00000002
RAX: 0000000000020007 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff8881084c4498 RDI: ffff8881084c3980
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8172c195
R10: ffffc900026375d8 R11: ffffffff81ac3aa0 R12: 00000000f6f446d9
R13: ffff8881084c4470 R14: ffff8881084c4498 R15: 9f544daacde78291
FS:  00007fe051b96380(0000) GS:ffff8880b8618000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc2aab2e000 CR3: 000000010e63e000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __lock_acquire+0xab9/0xd20
 lock_acquire+0x120/0x360
 unwind_next_frame+0xc2/0x2390
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5b/0x80
 kmem_cache_free+0x18f/0x400
 __unix_dgram_recvmsg+0x9f9/0xd60
 sock_recvmsg+0x22c/0x270
 sock_read_iter+0x231/0x2f0
 vfs_read+0x55a/0xa30
 ksys_read+0x145/0x250
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe051ceab6a
Code: 00 3d 00 00 41 00 75 0d 50 48 8d 3d 2d 08 0a 00 e8 ea 7d 01 00 31 c0 e9 07 ff ff ff 64 8b 04 25 18 00 00 00 85 c0 75 1b 0f 05 <48> 3d 00 f0 ff ff 76 6c 48 8b 15 8f a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffe95a0dc48 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fe051ceab6a
RDX: 00000000000000ff RSI: 000055eb03d55950 RDI: 0000000000000000
RBP: 000055eb03d55910 R08: 0000000000000800 R09: 0000000000000000
R10: 000055eb03d55f00 R11: 0000000000000246 R12: 000055eb03d55999
R13: 000055eb03d55950 R14: 0000000000000000 R15: 00007fe051ecfa80
 </TASK>
