INFO: task syz.4.1093:10744 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.1093      state:D stack:0     pid:10744 tgid:10743 ppid:10051  task_flags:0x400140 flags:0x00000011
Call trace:
 __switch_to+0x2b0/0x6e0 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x13c/0x20c kernel/sched/core.c:7326
 cgroup_lock_and_drain_offline+0x490/0x604 kernel/cgroup/cgroup.c:3275
 cgroup_kn_lock_live+0xbc/0x158 kernel/cgroup/cgroup.c:1715
 cgroup_subtree_control_write+0x258/0x990 kernel/cgroup/cgroup.c:3577
 cgroup_file_write+0x23c/0x6e4 kernel/cgroup/cgroup.c:4316
 kernfs_fop_write_iter+0x260/0x3b8 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x51c/0xa0c fs/read_write.c:687
 ksys_write+0x12c/0x228 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __arm64_sys_write+0x84/0x98 fs/read_write.c:747
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:738
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:757
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffff800088d171e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffff800088d171e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffff800088d171e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x4c/0x188 kernel/locking/lockdep.c:6775
1 lock held by klogd/4335:
2 locks held by getty/4496:
 #0: ffff0000c357c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff8000924fb2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x348/0xf78 drivers/tty/n_tty.c:2211
3 locks held by syz.4.1093/10744:
 #0: ffff0001040989b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x100/0x144 fs/file.c:1259
 #1: ffff0000c997e450 (sb_writers#8){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
 #1: ffff0000c997e450 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x248/0xa0c fs/read_write.c:683
 #2: ffff0000f2b1ec80 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1b0/0x3b8 fs/kernfs/file.c:336

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