INFO: task syz.8.66174:13269 blocked for more than 430 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.8.66174     state:D stack:0     pid:13269 tgid:13267 ppid:5785   task_flags:0x400040 flags:0x00000005
Call trace: 
[<81a3c95c>] (__schedule) from [<802972f4>] (__schedule_loop kernel/sched/core.c:7043 [inline])
[<81a3c95c>] (__schedule) from [<802972f4>] (rt_mutex_schedule+0x20/0x38 kernel/sched/core.c:7339)
 r10:855cec00 r9:00000002 r8:00000000 r7:dfb71dc0 r6:dfb71dc8 r5:85810c00
 r4:85810c00
[<802972d4>] (rt_mutex_schedule) from [<81a437d8>] (rt_mutex_slowlock_block.constprop.0+0x40/0x1d4 kernel/locking/rtmutex.c:1647)
 r5:85810c00 r4:8325dc54
[<81a43798>] (rt_mutex_slowlock_block.constprop.0) from [<81a44b30>] (__rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline])
[<81a43798>] (rt_mutex_slowlock_block.constprop.0) from [<81a44b30>] (__rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline])
[<81a43798>] (rt_mutex_slowlock_block.constprop.0) from [<81a44b30>] (rt_mutex_slowlock.constprop.0+0xd4/0x364 kernel/locking/rtmutex.c:1800)
 r10:60000013 r9:dfb71dc8 r8:00000002 r7:dfb71dc0 r6:8325dc54 r5:00000000
 r4:85810c00
[<81a44a5c>] (rt_mutex_slowlock.constprop.0) from [<81a44ea4>] (__rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline])
[<81a44a5c>] (rt_mutex_slowlock.constprop.0) from [<81a44ea4>] (__rt_mutex_lock_common kernel/locking/rtmutex_api.c:49 [inline])
[<81a44a5c>] (rt_mutex_slowlock.constprop.0) from [<81a44ea4>] (rt_mutex_lock+0x44/0x48 kernel/locking/rtmutex_api.c:89)
 r10:81ddd584 r9:00000000 r8:dfb71f68 r7:00000000 r6:dfb71e88 r5:00000001
 r4:8325dc40
[<81a44e60>] (rt_mutex_lock) from [<810cbf20>] (i2c_adapter_lock_bus+0x14/0x18 drivers/i2c/i2c-core-base.c:852)
[<810cbf0c>] (i2c_adapter_lock_bus) from [<810cdd14>] (i2c_lock_bus include/linux/i2c.h:809 [inline])
[<810cbf0c>] (i2c_adapter_lock_bus) from [<810cdd14>] (__i2c_lock_bus_helper drivers/i2c/i2c-core.h:46 [inline])
[<810cbf0c>] (i2c_adapter_lock_bus) from [<810cdd14>] (i2c_transfer+0x9c/0x110 drivers/i2c/i2c-core-base.c:2316)
[<810cdc78>] (i2c_transfer) from [<810cdde4>] (i2c_transfer_buffer_flags+0x5c/0x8c drivers/i2c/i2c-core-base.c:2348)
 r6:00000000 r5:00000010 r4:00000000
[<810cdd88>] (i2c_transfer_buffer_flags) from [<810d2d68>] (i2c_master_send include/linux/i2c.h:109 [inline])
[<810cdd88>] (i2c_transfer_buffer_flags) from [<810d2d68>] (i2cdev_write+0x70/0xb4 drivers/i2c/i2c-dev.c:183)
 r7:8be6d000 r6:863216c0 r5:00000010 r4:00000000
[<810d2cf8>] (i2cdev_write) from [<80553d68>] (vfs_write+0xac/0x44c fs/read_write.c:684)
 r7:85810c00 r6:00000000 r5:863216c0 r4:810d2cf8
[<80553cbc>] (vfs_write) from [<80554278>] (ksys_write+0x74/0xe8 fs/read_write.c:738)
 r10:00000004 r9:85810c00 r8:8020029c r7:00000000 r6:00000000 r5:863216c0
 r4:863216c1
[<80554204>] (ksys_write) from [<805542fc>] (__do_sys_write fs/read_write.c:749 [inline])
[<80554204>] (ksys_write) from [<805542fc>] (sys_write+0x10/0x14 fs/read_write.c:746)
 r7:00000004 r6:002f6308 r5:00000000 r4:00000000
[<805542ec>] (sys_write) from [<80200060>] (ret_fast_syscall+0x0/0x1c arch/arm/mm/proc-v7.S:67)
Exception stack(0xdfb71fa8 to 0xdfb71ff0)
1fa0:                   00000000 00000000 00000003 00000000 00000000 00000000
1fc0: 00000000 00000000 002f6308 00000004 002e0000 00000000 00006364 76f8c0bc
1fe0: 76f8bec0 76f8beb0 0001948c 001322c0
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 32 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT 
Hardware name: ARM-Versatile Express
Call trace: 
[<80201a24>] (dump_backtrace) from [<80201b20>] (show_stack+0x18/0x1c arch/arm/kernel/traps.c:257)
 r7:00000000 r6:00000013 r5:60000093 r4:82260504
[<80201b08>] (show_stack) from [<8021fb90>] (__dump_stack lib/dump_stack.c:94 [inline])
[<80201b08>] (show_stack) from [<8021fb90>] (dump_stack_lvl+0x70/0x7c lib/dump_stack.c:120)
[<8021fb20>] (dump_stack_lvl) from [<8021fbb4>] (dump_stack+0x18/0x1c lib/dump_stack.c:129)
 r5:00000000 r4:00000001
[<8021fb9c>] (dump_stack) from [<81a26570>] (nmi_cpu_backtrace+0x160/0x17c lib/nmi_backtrace.c:113)
[<81a26410>] (nmi_cpu_backtrace) from [<81a266bc>] (nmi_trigger_cpumask_backtrace+0x130/0x1d8 lib/nmi_backtrace.c:62)
 r7:00000000 r6:8280c690 r5:8281ac94 r4:ffffffff
[<81a2658c>] (nmi_trigger_cpumask_backtrace) from [<802304fc>] (arch_trigger_cpumask_backtrace+0x18/0x1c arch/arm/kernel/smp.c:852)
 r9:82abd564 r8:82804d40 r7:000a9240 r6:00007ef8 r5:8281b248 r4:8641200c
[<802304e4>] (arch_trigger_cpumask_backtrace) from [<8037d8dc>] (trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline])
[<802304e4>] (arch_trigger_cpumask_backtrace) from [<8037d8dc>] (check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline])
[<802304e4>] (arch_trigger_cpumask_backtrace) from [<8037d8dc>] (watchdog+0x4d4/0x81c kernel/hung_task.c:491)
[<8037d408>] (watchdog) from [<80281fcc>] (kthread+0x12c/0x280 kernel/kthread.c:463)
 r10:00000000 r9:00000000 r8:8037d408 r7:8334c800 r6:8334c800 r5:83391800
 r4:00000001
[<80281ea0>] (kthread) from [<80200114>] (ret_from_fork+0x14/0x20 arch/arm/kernel/entry-common.S:137)
Exception stack(0xdf8e1fb0 to 0xdf8e1ff8)
1fa0:                                     00000000 00000000 00000000 00000000
1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
 r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:80281ea0
 r4:8334acc0
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 2842 Comm: pr/ttyAMA-1 Not tainted syzkaller #0 PREEMPT 
Hardware name: ARM-Versatile Express
PC is at __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
PC is at _raw_spin_unlock_irqrestore+0x28/0x54 kernel/locking/spinlock.c:194
LR is at spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
LR is at __uart_port_unlock_irqrestore include/linux/serial_core.h:616 [inline]
LR is at pl011_console_device_unlock+0x20/0x24 drivers/tty/serial/amba-pl011.c:2603
pc : [<81a46924>]    lr : [<80a79720>]    psr: 60000013
sp : eba91eb0  ip : eba91ec0  fp : eba91ebc
r10: 82959194  r9 : 00000001  r8 : 00000000
r7 : 00000117  r6 : 829590f8  r5 : 00000000  r4 : 00000001
r3 : 00001fe8  r2 : 00000000  r1 : 60000013  r0 : 841e3840
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 30c5387d  Table: 866b0900  DAC: 00000000
Call trace: 
[<81a468fc>] (_raw_spin_unlock_irqrestore) from [<80a79720>] (spin_unlock_irqrestore include/linux/spinlock.h:406 [inline])
[<81a468fc>] (_raw_spin_unlock_irqrestore) from [<80a79720>] (__uart_port_unlock_irqrestore include/linux/serial_core.h:616 [inline])
[<81a468fc>] (_raw_spin_unlock_irqrestore) from [<80a79720>] (pl011_console_device_unlock+0x20/0x24 drivers/tty/serial/amba-pl011.c:2603)
[<80a79700>] (pl011_console_device_unlock) from [<802e44ac>] (nbcon_emit_one+0x88/0x100 kernel/printk/nbcon.c:1142)
[<802e4424>] (nbcon_emit_one) from [<802e46cc>] (nbcon_kthread_func+0x1a8/0x2a4 kernel/printk/nbcon.c:1229)
 r6:8280c690 r5:84ae0000 r4:829590f8
[<802e4524>] (nbcon_kthread_func) from [<80281fcc>] (kthread+0x12c/0x280 kernel/kthread.c:463)
 r10:00000000 r9:829590f8 r8:802e4524 r7:847cb200 r6:847cb200 r5:84ae0000
 r4:00000001
[<80281ea0>] (kthread) from [<80200114>] (ret_from_fork+0x14/0x20 arch/arm/kernel/entry-common.S:137)
Exception stack(0xeba91fb0 to 0xeba91ff8)
1fa0:                                     00000000 00000000 00000000 00000000
1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
 r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:80281ea0
 r4:84748580