INFO: task syz.0.2896:13242 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.2896      state:D stack:28400 pid:13242 tgid:13241 ppid:5849   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1350
 bdev_open+0xe0/0xd30
 bdev_file_open_by_dev+0x1be/0x240
 bdev_file_open_by_path+0x1cc/0x4d0
 btrfs_scan_one_device+0xa6/0x650
 btrfs_get_tree+0x433/0x1820
 vfs_get_tree+0x92/0x2b0
 do_new_mount+0x2a2/0x9e0
 __se_sys_mount+0x317/0x410
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2427f8ebe9
RSP: 002b:00007f2428ea7038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f24281c5fa0 RCX: 00007f2427f8ebe9
RDX: 0000200000000040 RSI: 0000200000000100 RDI: 0000200000000000
RBP: 00007f2428011e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f24281c6038 R14: 00007f24281c5fa0 R15: 00007ffd8ec76168
 </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 getty/5676:
 #0: ffff88801fe200a0 (&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
1 lock held by udevd/6093:
 #0: ffff888020594358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
2 locks held by syz.0.2896/13242:
 #0: ffffffff8e6e3e88 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x408/0x1820
 #1: ffff888020594358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
1 lock held by syz.4.2917/13293:
 #0: ffffffff8e6e3e88 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x408/0x1820
1 lock held by syz.5.3178/14009:
 #0: ffffffff8e6e3e88 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x408/0x1820
1 lock held by syz.7.3214/14113:
 #0: ffffffff8e6e3e88 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x408/0x1820
1 lock held by syz.1.3267/14338:
 #0: ffffffff8e6e3e88 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x408/0x1820
1 lock held by syz.9.3621/15207:
 #0: ffffffff8e6e3e88 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x408/0x1820
1 lock held by syz.2.3749/15508:
 #0: ffffffff8e6e3e88 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x408/0x1820
1 lock held by syz.0.3847/15754:
 #0: ffff888020594358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
1 lock held by syz.4.3888/15882:
 #0: ffffffff8e6e3e88 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x408/0x1820
1 lock held by syz.3.3901/15909:
 #0: ffffffff8e6e3e88 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x408/0x1820

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

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: 0 Comm: swapper/0 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:pv_native_safe_halt+0x13/0x20
Code: 53 e7 02 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d 73 67 0e 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff8de07d80 EFLAGS: 00000282
RAX: a3977ec258b7ae00 RBX: ffffffff819683c8 RCX: a3977ec258b7ae00
RDX: 0000000000000001 RSI: ffffffff8d9b8241 RDI: ffffffff8be33880
RBP: ffffffff8de07eb8 R08: ffff88804b032f9b R09: 1ffff110096065f3
R10: dffffc0000000000 R11: ffffed10096065f4 R12: ffffffff8fa39030
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1bd2a20
FS:  0000000000000000(0000) GS:ffff8880b8618000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055556bd1a5c8 CR3: 00000001079b6000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 default_idle+0x13/0x20
 default_idle_call+0x74/0xb0
 do_idle+0x1e8/0x510
 cpu_startup_entry+0x44/0x60
 rest_init+0x2de/0x300
 start_kernel+0x3a9/0x410
 x86_64_start_reservations+0x24/0x30
 x86_64_start_kernel+0x143/0x1c0
 common_startup_64+0x13e/0x147
 </TASK>
