BTRFS: device fsid ecf6f2a3-2997-48ae-b81e-1b00920efd9a devid 0 transid 0 /dev/loop1
INFO: task syz-executor1:25709 blocked for more than 120 seconds.
      Not tainted 4.9.94-g8683408 #3
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor1   D26808 25709   3696 0x20020004
 ffff8801d5661800 ffff8801c60daa00 ffff8801a3c29f80 ffff8801a1439800
 ffff8801db321b98 ffff8801d3537070 ffffffff838c040d 0000000041b58ab3
 ffffffff841a49d8 ffffffff81234350 0000000000000001 ffff8801db322468
Call Trace:
 [<ffffffff838c1a0f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff838cde21>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff838bfbea>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5180
 [<ffffffff838c2e59>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff838c2e59>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff838c25a3>] __wait_on_bit+0x93/0x120 kernel/sched/wait.c:383
 [<ffffffff838c28d8>] out_of_line_wait_on_bit+0xe8/0x120 kernel/sched/wait.c:396
 [<ffffffff816263e1>] wait_on_bit_io include/linux/wait.h:1070 [inline]
 [<ffffffff816263e1>] __wait_on_buffer fs/buffer.c:124 [inline]
 [<ffffffff816263e1>] wait_on_buffer include/linux/buffer_head.h:347 [inline]
 [<ffffffff816263e1>] __bread_slow fs/buffer.c:1229 [inline]
 [<ffffffff816263e1>] __bread_gfp+0x221/0x270 fs/buffer.c:1423
 [<ffffffff819f8c11>] __bread include/linux/buffer_head.h:389 [inline]
 [<ffffffff819f8c11>] btrfs_read_dev_one_super+0xa1/0x270 fs/btrfs/disk-io.c:3359
 [<ffffffff819f8e4c>] btrfs_read_dev_super.part.52+0x6c/0xd0 fs/btrfs/disk-io.c:3394
 [<ffffffff819f8ec5>] btrfs_read_dev_super+0x15/0x20 fs/btrfs/disk-io.c:3380
 [<ffffffff81a8855e>] btrfs_get_bdev_and_sb+0xde/0x2e0 fs/btrfs/volumes.c:304
 [<ffffffff81a8891a>] __btrfs_open_devices+0x1ba/0xab0 fs/btrfs/volumes.c:986
 [<ffffffff81a8e9e2>] btrfs_open_devices+0xa2/0xb0 fs/btrfs/volumes.c:1059
 [<ffffffff81981865>] btrfs_mount+0xe45/0x2bc0 fs/btrfs/super.c:1603
 [<ffffffff8157b99c>] mount_fs+0x28c/0x370 fs/super.c:1206
 [<ffffffff815daf41>] vfs_kern_mount.part.29+0xd1/0x3d0 fs/namespace.c:991
 [<ffffffff815db280>] vfs_kern_mount+0x40/0x60 fs/namespace.c:973
 [<ffffffff81980e2b>] mount_subvol fs/btrfs/super.c:1395 [inline]
 [<ffffffff81980e2b>] btrfs_mount+0x40b/0x2bc0 fs/btrfs/super.c:1566
 [<ffffffff8157b99c>] mount_fs+0x28c/0x370 fs/super.c:1206
 [<ffffffff815daf41>] vfs_kern_mount.part.29+0xd1/0x3d0 fs/namespace.c:991
 [<ffffffff815e2869>] vfs_kern_mount fs/namespace.c:973 [inline]
 [<ffffffff815e2869>] do_new_mount fs/namespace.c:2512 [inline]
 [<ffffffff815e2869>] do_mount+0x3c9/0x2740 fs/namespace.c:2834
 [<ffffffff8168196c>] C_SYSC_mount fs/compat.c:810 [inline]
 [<ffffffff8168196c>] compat_SyS_mount+0x4fc/0xff0 fs/compat.c:775
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff838d2a10>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

Showing all locks held in the system:
2 locks held by khungtaskd/515:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646bc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646bc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81423bb0>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3514:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d565c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3610:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838cf4b2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82007082>] n_tty_read+0x202/0x16b0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor1/25709:
 #0:  (uuid_mutex){+.+.+.}, at: [<ffffffff81a8e967>] btrfs_open_devices+0x27/0xb0 fs/btrfs/volumes.c:1054

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

NMI backtrace for cpu 1
CPU: 1 PID: 515 Comm: khungtaskd Not tainted 4.9.94-g8683408 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d973fd08 ffffffff81d9b509 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b7d60 ffff8801d973fd40
 ffffffff81da6837 0000000000000001 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81d9b509>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d9b509>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81da6837>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81da67ca>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b7e64>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81364c54>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81364c54>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81364c54>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81364c54>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ad2d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838d14dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.94-g8683408 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84429800 task.stack: ffffffff84400000
RIP: 0010:[<ffffffff8122ddfe>] 
c [<ffffffff8122ddfe>] match_held_lock+0x4e/0x570 kernel/locking/lockdep.c:3408
RSP: 0018:ffff8801db207bd0  EFLAGS: 00000083
RAX: dffffc0000000000 RBX: ffffffff84429800 RCX: 0000000000000000
RDX: ffffffff8442a0ea RSI: ffffffff844deea0 RDI: ffffffff8442a0ea
RBP: ffff8801db207c00 R08: 0000000000000001 R09: 000000000000000e
R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff0885418
R13: ffffffff8442a0c8 R14: ffffffff844deea0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007faac4ee7140 CR3: 00000001c9c14000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d45518a8
c ffffffff84429800
c fffffbfff0885418
c ffffffff8442a0c8
c
 ffffffff844deea0
c 0000000000000000
c ffff8801db207c40
c ffffffff8122e3c2
c
 ffffffff8442a0c0
c 0000000000000046
c ffffffff84429800
c ffffffff844deea0
c
Call Trace:
 <IRQ> 
d [<ffffffff8122e3c2>] __lock_is_held+0xa2/0xf0 kernel/locking/lockdep.c:3597
 [<ffffffff8122ebf4>] lock_is_held+0xb4/0x140 kernel/locking/lockdep.c:3794
 [<ffffffff8127a243>] rcu_read_lock_sched_held+0x103/0x120 kernel/rcu/update.c:112
 [<ffffffff811e7c81>] trace_sched_contrib_scale_f include/trace/events/sched.h:590 [inline]
 [<ffffffff811e7c81>] __update_load_avg kernel/sched/fair.c:2873 [inline]
 [<ffffffff811e7c81>] update_cfs_rq_load_avg+0xd41/0x1f10 kernel/sched/fair.c:3291
 [<ffffffff811f016a>] update_blocked_averages+0x26a/0x520 kernel/sched/fair.c:8201
 [<ffffffff81205884>] rebalance_domains+0xe4/0xbc0 kernel/sched/fair.c:10075
 [<ffffffff81206659>] run_rebalance_domains+0x2f9/0x510 kernel/sched/fair.c:10332
 [<ffffffff838d7efb>] __do_softirq+0x20b/0x937 kernel/softirq.c:284
 [<ffffffff81149037>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff81149037>] irq_exit+0x147/0x190 kernel/softirq.c:405
 [<ffffffff838d5aa1>] smp_reschedule_interrupt+0x71/0x90 arch/x86/kernel/smp.c:270
 [<ffffffff838d3610>] reschedule_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:671
 <EOI> 
d [<ffffffff838cff16>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
 [<ffffffff838cf555>] arch_safe_halt arch/x86/include/asm/paravirt.h:104 [inline]
 [<ffffffff838cf555>] default_idle+0x55/0x360 arch/x86/kernel/process.c:295
 [<ffffffff81069fa0>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:286
 [<ffffffff838d0375>] default_idle_call+0x45/0x60 kernel/sched/idle.c:97
 [<ffffffff81220e35>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff81220e35>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff81220e35>] cpu_startup_entry+0x2b5/0x380 kernel/sched/idle.c:303
 [<ffffffff838bd1dc>] rest_init+0x183/0x189 init/main.c:409
 [<ffffffff84a73943>] start_kernel+0x67e/0x6b2 init/main.c:664
 [<ffffffff84a7229a>] x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:196
 [<ffffffff84a723db>] x86_64_start_kernel+0x13f/0x162 arch/x86/kernel/head64.c:177
Code: 
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c