INFO: task syz.4.69:6997 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.69        state:D stack:0     pid:6997  tgid:6996  ppid:6570   task_flags:0x400140 flags:0x00000011
Call trace:
 __switch_to+0x418/0x87c arch/arm64/kernel/process.c:741 (T)
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1250/0x2a7c kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0xb4/0x230 kernel/sched/core.c:6960
 schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:7017
 __mutex_lock_common+0xd04/0x2678 kernel/locking/mutex.c:692
 __mutex_lock kernel/locking/mutex.c:776 [inline]
 mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:828
 sync_bdevs+0x210/0x3f0 block/bdev.c:1305
 ksys_sync+0xb8/0x164 fs/sync.c:105
 __arm64_sys_sync+0x14/0x24 fs/sync.c:113
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x5c/0x26c arch/arm64/kernel/entry-common.c:724
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

Showing all locks held in the system:
1 lock held by khungtaskd/32:
 #0: ffff80008fa5b520 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x4/0x48 include/linux/rcupdate.h:330
3 locks held by kworker/u8:14/3543:
1 lock held by klogd/6196:
2 locks held by getty/6350:
 #0: ffff0000d62c40a0 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff800099ee02f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x34c/0xfc8 drivers/tty/n_tty.c:2211
3 locks held by kworker/1:4/6680:
2 locks held by kworker/1:5/6685:
1 lock held by udevd/6720:
 #0: ffff0000cc5a0358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xcc/0xc20 block/bdev.c:962
1 lock held by syz.4.69/6997:
 #0: ffff0000cc5a0358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x210/0x3f0 block/bdev.c:1305

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