INFO: task syz-executor:6038 blocked for more than 143 seconds.
      Not tainted syzkaller #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:18856 pid:6038  tgid:6038  ppid:1      task_flags:0x40014c flags:0x00004002
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 wb_wait_for_completion+0x15f/0x260
 sync_inodes_sb+0x1bb/0xa10
 sync_filesystem+0x17a/0x230
 generic_shutdown_super+0x6f/0x2c0
 kill_block_super+0x44/0x90
 ext4_kill_sb+0x68/0xb0
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x425/0x4c0
 task_work_run+0x1d4/0x260
 do_exit+0x6b5/0x2300
 do_group_exit+0x21c/0x2d0
 __x64_sys_exit_group+0x3f/0x40
 x64_sys_call+0x21f7/0x2200
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7d90f8eba9
RSP: 002b:00007fff40382868 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f7d91011c77 RCX: 00007f7d90f8eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000010 R08: 00007fff40380606 R09: 00007fff40383b20
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff40383b20
R13: 00007f7d91011c05 R14: 0000555586c644a8 R15: 00007fff40384bf0
 </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
5 locks held by kworker/u9:3/89:
 #0: ffff88801b337948 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000172fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff888041524b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x1cc/0x350
 #3: ffff88801dcd8270 (&ei->i_data_sem){++++}-{4:4}, at: ext4_map_blocks+0x765/0x1740
 #4: ffffffff8e13a0e0 (rcu_read_lock){....}-{1:3}, at: __queue_work+0x102/0xfb0
4 locks held by kworker/u10:5/3626:
2 locks held by getty/5679:
 #0: ffff88810ecc60a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900026e82f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
2 locks held by syz-executor/6038:
 #0: ffff8880385400e0 (&type->s_umount_key#31){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
 #1: ffff8881074ba7d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x19f/0xa10
2 locks held by syz-executor/9630:
 #0: ffff8881246b40e0 (&type->s_umount_key#31){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
 #1: ffff8880219647d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x19f/0xa10
3 locks held by kworker/0:6/10242:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90002f4fbc0 (key_gc_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8e13fb78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730

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

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: 23 Comm: ksoftirqd/1 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_release+0x29a/0x3e0
Code: c7 b2 93 ba 8d e8 a6 f1 dc 09 b8 ff ff ff ff 65 0f c1 05 49 6f 03 11 83 f8 01 75 51 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 <f7> 44 24 20 00 02 00 00 75 56 f7 c3 00 02 00 00 74 01 fb 65 48 8b
RSP: 0018:ffffc900001b72d0 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000002 RCX: a51eb2cc03827100
RDX: 0000000000000001 RSI: ffffffff8dba93b2 RDI: ffffffff8be33e80
RBP: ffff88810002e158 R08: 0000000000000015 R09: ffffffff8172d195
R10: ffffc900001b7458 R11: ffffffff81ac4b00 R12: 0000000000000001
R13: 0000000000000001 R14: ffffffff8e13a0e0 R15: ffff88810002d640
FS:  0000000000000000(0000) GS:ffff8881a3c15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f61bff8 CR3: 0000000023c14000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 unwind_next_frame+0x19a9/0x2390
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 kasan_save_stack+0x3e/0x60
 kasan_record_aux_stack+0xbd/0xd0
 call_rcu+0x157/0x9c0
 kmem_cache_free+0x309/0x400
 blk_update_request+0x57e/0xe60
 blk_mq_end_request+0x3e/0x70
 blk_flush_complete_seq+0x678/0xcc0
 flush_end_io+0xbaf/0xe60
 __blk_mq_end_request+0x46a/0x630
 blk_done_softirq+0x10a/0x160
 handle_softirqs+0x286/0x870
 run_ksoftirqd+0x9b/0x100
 smpboot_thread_fn+0x542/0xa60
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
