INFO: task syz.7.1199:9552 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.1199      state:D stack:0     pid:9552  tgid:9551  ppid:8467   task_flags:0x400140 flags:0x00000011
Call trace:
 __switch_to+0x2b4/0x6e4 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5533 [inline]
 __schedule+0x135c/0x2b00 kernel/sched/core.c:7284
 __schedule_loop kernel/sched/core.c:7361 [inline]
 schedule+0x13c/0x20c kernel/sched/core.c:7376
 cgroup_lock_and_drain_offline+0x490/0x604 kernel/cgroup/cgroup.c:3350
 cgroup_kn_lock_live+0xbc/0x158 kernel/cgroup/cgroup.c:1717
 cgroup_subtree_control_write+0x258/0x990 kernel/cgroup/cgroup.c:3652
 cgroup_file_write+0x23c/0x6e4 kernel/cgroup/cgroup.c:4412
 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+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796
 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606

Showing all locks held in the system:
locks held by khungtaskd/31: 1, last CPU#1:
 #0: ffff800088c618e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff800088c618e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff800088c618e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x4c/0x188 kernel/locking/lockdep.c:6871
locks held by getty/4490: 2, on CPU#0:
 #0: ffff0000cd9510a0 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff80009246e2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x348/0xf78 drivers/tty/n_tty.c:2211
locks held by syz.7.1199/9552: 3, on CPU#0:
 #0: ffff0000d8f8cd30 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x100/0x144 fs/file.c:1259
 #1: ffff0000d394e460 (sb_writers#8){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
 #1: ffff0000d394e460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x248/0xa0c fs/read_write.c:683
 #2: ffff0000ef30e480 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1b0/0x3b8 fs/kernfs/file.c:336
locks held by syz-executor/9746: 1, last CPU#0:
 #0: ffff0000c55ee0e8 (&type->s_umount_key#32){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff0000c55ee0e8 (&type->s_umount_key#32){++++}-{4:4}, at: __super_lock_excl fs/super.c:75 [inline]
 #0: ffff0000c55ee0e8 (&type->s_umount_key#32){++++}-{4:4}, at: deactivate_super+0xcc/0xf4 fs/super.c:613
locks held by syz.1.2185/13582: 4, last CPU#0:
 #0: ffff0000d21b0e70 (&u->iolock){+.+.}-{4:4}, at: __unix_dgram_recvmsg+0x18c/0x85c net/unix/af_unix.c:2587
 #1: ffff0000d21b0f98 (&u->peer_wait){+.+.}-{3:3}, at: __wake_up_common_lock+0x30/0x78 kernel/sched/wait.c:125
 #2: ffff0000c8a1a7b8 (&p->pi_lock){-.-.}-{2:2}, at: class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:595 [inline]
 #2: ffff0000c8a1a7b8 (&p->pi_lock){-.-.}-{2:2}, at: try_to_wake_up+0x68/0xdc4 kernel/sched/core.c:4315
 #3: ffff0001adee21e0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2c/0x44 kernel/sched/core.c:677

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